Ah, very good idea, thanks!  I'd forgotten about the Wayback Machine.  It says it has 105 instances of www.doepfer.de/a100.htm ranging from May 1997 to November 2016, so that will be very helpful.  Examining which modules in the table have links seems to be the key.  This should provide dates that will be fairly close and perhaps only a few months after the actual release dates.

Before I spend hours of detective work using the Wayback Machine, if anyone here has more exact release dates on the modules, please let me know. :-)

Thanks,
   - Eric