How about the actual-active and posting members to inactive members ratio?
Depends what you define active. Anyway, I'm pretty sure you're stuck with going through every profile and finding that out yourself. Bit low on the priority list to make/apply something to do so easily.
When I said "Actual Members", what I meant was : People who have actually played this game and had created a forums account regardless of "post" counts. As for active players, I defined them: as players who actualy log on; regardless of even posting. But it really depends what people call active these days, like Cameron said. There are players who log on forums maybe once a year; there are also people who log in on forums every 6 months and so forth. The best way to evaluate this is by looking at the daily users who have logged on the forums, which today was 52. About average these days, the amount of players who log on forums has actually increased in the past 3 years. Last year the amount of players who use to log on every day was on average, which is through observing, 20>x>30. Last year and 2012 the highest log in I ever saw was like 50, I believe exlucding that whole "oldschool reuinon". I've noticed that the forums this year has increased, about 30+ log on each day. Just abit of info if you wanted to know.