Arjuna,
Your approach to have an idea of a community's activity by combining some
metrics is interesting. Also, to compare monthly averages instead of end of
year performance is also good.
*Increase in database size, number of most active contributors (making more
than 100 edits a month) and page views can be real indicators of growth and
activity*. Is there any way to find database size? We don't have that and
many other useful stats after May 2010. Check
http://stats.wikimedia.org/EN/TablesWikipediaTA.htm for example.
Also, any inference based on page views should normalize it based on the
population of native speaking people to have a better perspective of the
community's performance compared to its potential / size.
Ravi