Damn you - this is exactly the sort of question that brings out the inner data nerd in me… 😆 🤓
This is a difficult question to answer fairly. Let me explain my thoughts on this - bearing in mind that there were 12+ years of the previous forum, and over that time about 1,450 members signed up - many of which would have been active for only a short period of time and therefore inactive at the decline of the old forum.
Instead, we should probably consider the recent users - and for that, let's assume we mean since the start of 2020.
So - at the moment, we have 36 signed up members, myself included.
Between 1st January 2020 and 1st June 2024, 248 users posted messages (on the old forum). Of those 248 users, 19 have re-registered their accounts on the new forum, so it could be said that say that the answer is 7.6% (19/248), but even that's probably unfair, because there will still have been some inactive users in that four and a bit year period.
Here's the breakdown of posts between 1st Jan 2020 and 1st Jun 2024:
+---------------------+-----------------+----------------+
| username | number_of_posts | status |
+---------------------+-----------------+----------------+
| griff851 | 271 | NOT registered |
| Mr.R | 241 | registered |
| Rudy | 200 | NOT registered |
| RWG | 181 | registered |
| Bridgland | 161 | registered |
| tubbylad | 161 | NOT registered |
| Ducal | 129 | NOT registered |
| stiglarsenDK | 123 | NOT registered |
| marvin | 119 | registered |
| brad black | 109 | NOT registered |
| lefty | 102 | NOT registered |
| Seadweller | 86 | NOT registered |
| jakepeewee | 84 | NOT registered |
| firefly_1965 | 79 | NOT registered |
| MarkT | 77 | NOT registered |
| outtacontrolla | 70 | NOT registered |
| econti | 66 | NOT registered |
| freqrider | 64 | registered |
| Steben | 62 | NOT registered |
| ducati dad | 61 | NOT registered |
| henk | 56 | NOT registered |
| Jasper | 52 | registered |
| AJV | 52 | NOT registered |
| dudlington | 50 | NOT registered |
| KevB | 49 | registered |
| hindsight | 48 | registered |
| tboooe | 46 | registered |
| surfking | 43 | NOT registered |
| Whitto1 | 42 | NOT registered |
| johnboy888 | 39 | NOT registered |
| AndrewS | 37 | NOT registered |
| haga40 | 37 | NOT registered |
| Nux | 33 | NOT registered |
| nine16 | 32 | registered |
| RON816 | 32 | NOT registered |
| countcoupe | 29 | NOT registered |
| eric | 29 | NOT registered |
| lakeman | 28 | NOT registered |
| Fulvia-hf | 27 | NOT registered |
| Speedmade | 25 | NOT registered |
| 900SL | 23 | registered |
| Jafa | 23 | NOT registered |
| pht9 | 22 | NOT registered |
| Wfieldin | 20 | NOT registered |
| mikesps | 20 | registered |
| Bish | 19 | NOT registered |
| nalimugmug | 18 | NOT registered |
| MatthiB | 17 | NOT registered |
| desmophil | 16 | NOT registered |
| MickB | 16 | NOT registered |
| werner | 16 | NOT registered |
| Toni851 | 16 | NOT registered |
| cmd | 15 | NOT registered |
| Davo | 15 | NOT registered |
| Darkness | 15 | NOT registered |
| danbrisbane | 15 | NOT registered |
| alsar59 | 14 | NOT registered |
| glenn Twite | 14 | NOT registered |
| flinty | 14 | NOT registered |
| rodericb | 14 | NOT registered |
| jcgodefroy | 14 | NOT registered |
| DezmoDog | 13 | NOT registered |
| patrick | 12 | registered |
| ajcorse | 11 | NOT registered |
| jsedacca | 11 | NOT registered |
| workslorenz | 11 | NOT registered |
| Matt888 | 11 | registered |
| Elcondor | 11 | NOT registered |
| hedge hog | 10 | NOT registered |
| ducfactory | 10 | NOT registered |
| chris ardern | 10 | NOT registered |
| gio655 | 10 | NOT registered |
| JImmySL | 9 | registered |
| Jimmy | 9 | NOT registered |
| Claire4dukes | 9 | NOT registered |
| wastegate | 9 | NOT registered |
| Bambara | 8 | NOT registered |
| PTwo | 8 | NOT registered |
| Carts | 8 | registered |
| princefritz | 8 | NOT registered |
| Birdie | 8 | NOT registered |
| Peter888 | 7 | NOT registered |
| trogg888 | 7 | NOT registered |
| huit | 7 | NOT registered |
| Redbikemad1 | 7 | NOT registered |
| Tony IOM | 7 | NOT registered |
| SmartRacer | 7 | NOT registered |
| Rochducati | 6 | NOT registered |
| teddy | 6 | NOT registered |
| Theductor851 | 6 | NOT registered |
| JoeGoodson | 6 | NOT registered |
| D4RKO | 6 | registered |
| jlduck | 6 | NOT registered |
| stafford | 6 | NOT registered |
| BTD | 6 | NOT registered |
| Frank851 | 5 | NOT registered |
| crankyroller | 5 | NOT registered |
| Chris | 5 | NOT registered |
| carmat | 5 | NOT registered |
| Mautsen | 5 | NOT registered |
| Doug_ | 5 | NOT registered |
| CanuckVet | 5 | NOT registered |
| neil.ekberg | 5 | NOT registered |
| nodrog | 5 | NOT registered |
| desmodan | 5 | NOT registered |
| BARONROJO | 5 | NOT registered |
| sagot | 5 | NOT registered |
| bus | 5 | NOT registered |
| italian888 | 5 | NOT registered |
| aintgotitmusthaveit | 5 | NOT registered |
| Nasher | 5 | NOT registered |
| JSR29 | 5 | NOT registered |
| turbokiller | 5 | NOT registered |
| Deanw46 | 5 | NOT registered |
| rick1127 | 4 | NOT registered |
| Fuzzer74 | 4 | NOT registered |
| P47_Thunderbolt | 4 | NOT registered |
| adie851 | 4 | NOT registered |
| 851 tricolore | 4 | NOT registered |
| PatBig | 4 | NOT registered |
| Federico888 | 4 | NOT registered |
| jgautney | 4 | NOT registered |
| horst | 4 | NOT registered |
| ZAM851 | 4 | NOT registered |
| Kamenrider | 4 | NOT registered |
| jcmduc | 4 | NOT registered |
| alan.r | 4 | NOT registered |
| inchoate | 4 | NOT registered |
| Neil | 4 | NOT registered |
| Danger Mouse | 4 | NOT registered |
| lordmoonpie | 4 | NOT registered |
| Tor | 3 | NOT registered |
| MDDIXON | 3 | NOT registered |
| Craigm | 3 | NOT registered |
| RC2 | 3 | NOT registered |
| Ube | 3 | NOT registered |
| Acky | 3 | NOT registered |
| Cal | 3 | NOT registered |
| Rare66 | 3 | NOT registered |
| sp04 | 3 | NOT registered |
| erthmvr888 | 3 | NOT registered |
| RS02 | 3 | NOT registered |
| vale | 3 | NOT registered |
| Dictrilli | 3 | NOT registered |
| hauge | 3 | NOT registered |
| BABA | 3 | NOT registered |
| zwantedone | 3 | NOT registered |
| Kurt1964 | 3 | NOT registered |
| Tim K | 3 | NOT registered |
| SPO | 3 | NOT registered |
| Pacman | 3 | NOT registered |
| Grinta | 3 | NOT registered |
| jrduc996 | 3 | NOT registered |
| tiz851 | 3 | NOT registered |
| Philippe | 3 | NOT registered |
| Robbie | 2 | NOT registered |
| Higgins | 2 | NOT registered |
| Ben Bostrom | 2 | NOT registered |
| rxs51 | 2 | NOT registered |
| tian647 | 2 | NOT registered |
| firebird | 2 | NOT registered |
| rgpjs11 | 2 | NOT registered |
| trippel8 | 2 | NOT registered |
| desmolele | 2 | NOT registered |
| Jack L | 2 | NOT registered |
| RedOfCourse | 2 | NOT registered |
| Pat 851 SP3 | 2 | NOT registered |
| Bud977 | 2 | NOT registered |
| maclberry | 2 | NOT registered |
| Mr Amstel | 2 | NOT registered |
| EV916 | 2 | NOT registered |
| fabSP4 | 2 | NOT registered |
| nix510 | 2 | NOT registered |
| stevef. | 2 | NOT registered |
| motolaco | 2 | NOT registered |
| ducati75 | 2 | NOT registered |
| turning_base | 2 | NOT registered |
| george851 | 2 | NOT registered |
| Sludger | 2 | NOT registered |
| Duffy21690 | 2 | NOT registered |
| Bulu904 | 2 | NOT registered |
| Jahhx | 2 | NOT registered |
| Diesel | 2 | NOT registered |
| Dutchy888 | 2 | NOT registered |
| Desmonut | 2 | NOT registered |
| V8 lawman | 2 | NOT registered |
| MarcusT70 | 2 | NOT registered |
| phil_h | 1 | NOT registered |
| RichardE | 1 | NOT registered |
| Kristoffj | 1 | NOT registered |
| Dave H | 1 | NOT registered |
| cheshire cat | 1 | NOT registered |
| persp5 | 1 | NOT registered |
| baker7569 | 1 | NOT registered |
| AndyW | 1 | NOT registered |
| oliveakamomo | 1 | NOT registered |
| duc82 | 1 | NOT registered |
| Andya | 1 | NOT registered |
| BobGee | 1 | NOT registered |
| diabolik | 1 | registered |
| Mick_ducati_888 | 1 | NOT registered |
| Flat-12 | 1 | NOT registered |
| jagalfa | 1 | NOT registered |
| lochnagar | 1 | NOT registered |
| Scout666 | 1 | NOT registered |
| Multinet | 1 | NOT registered |
| germanfridris | 1 | NOT registered |
| gr1ffn | 1 | NOT registered |
| peer888sp4 | 1 | NOT registered |
| Privateer | 1 | NOT registered |
| STANG | 1 | NOT registered |
| Gads | 1 | NOT registered |
| mrc.engr | 1 | NOT registered |
| toospeed | 1 | NOT registered |
| ducatiguzzi | 1 | NOT registered |
| GPK | 1 | NOT registered |
| robbiano | 1 | NOT registered |
| Maxsam | 1 | NOT registered |
| tom900s | 1 | NOT registered |
| AndyPandy | 1 | NOT registered |
| Tric | 1 | NOT registered |
| 888Toni | 1 | NOT registered |
| eonderde | 1 | NOT registered |
| hnracing | 1 | NOT registered |
| simonr | 1 | NOT registered |
| Paul H | 1 | NOT registered |
| FarCough | 1 | NOT registered |
| cl955 | 1 | NOT registered |
| Jon Wright | 1 | registered |
| desmax888 | 1 | NOT registered |
| craigw | 1 | NOT registered |
| riki | 1 | NOT registered |
| Mr Tea | 1 | NOT registered |
| GRSH1980 | 1 | NOT registered |
| Loti34 | 1 | NOT registered |
| KB888SP5 | 1 | NOT registered |
| 851GC | 1 | NOT registered |
| MONTY | 1 | NOT registered |
| Weed | 1 | NOT registered |
| Meltonmiles | 1 | NOT registered |
| heizer300 | 1 | NOT registered |
| Robho | 1 | NOT registered |
| desmojon 851 | 1 | NOT registered |
| ChasT | 1 | NOT registered |
| ftanguis | 1 | NOT registered |
| jazunic | 1 | NOT registered |
| micholston | 1 | NOT registered |
| superlight825 | 1 | NOT registered |
+---------------------+-----------------+----------------+