Below is an updated version of the table posted by David Whyld (http://shadowvault.net/prolific.htm).
It was updated using data from the archives of Richard Otter's Delron site (http://www.delron.org.uk/adrift-games.htm).
According to this data, the ADRIFT community has (or has had) 232 authors and produced 540 games.
For more information (names of authors & games), you can check out this spreadsheet, but this should give authors an idea of how the community's production is distributed overall.
I'm at three-- where are you?