Just out of interest, I've been looking at two pages on the CDS website, Current and former Chancellors and Current and former RA members, to get a sense of who they are, how many times they've had a go, and whether they're still around. I copied the names into a Google Sheet and counted them up.
You can see all the names on the pivot tables on the different tabs, but basically across the 20 years and 40 terms, we've only had 16 different citizens be Chancellors (some more times than others) and seven of them are still here. And we've had 84 different citizens be RA members (some more times than others), and 24 of them are still here.
(A caveat here would be that some citizens' names have changed since they first appeared on those webpages and may now not match with the latest census. I've adjusted the ones I know about in my spreadsheet, but I may have missed some.)