Some complementing data on users from Swedish Wikipedia,
-Youngsters 15-22- high turnover & somewhat decreasing volume - do vandal fighting, write of computer games, music, film, sport etc (and these areas are worthy of respect too)
-Middle aged 22-50 --An increasing number of low volume contributers --A decrease of contributions from regular users, as there are fewer "empty" spaces for amateur masscontributions (medium turnover)
Mature 50+, low turnover which means over time both growing numbers and growing number of contributions per user
So we also see a decrease of mass article contributers in the age span 25-35 and a steady increase of contributions from 50+ers (but we still get valuable contributions from all age groups) Anders