Until the y-axis is normalized to account for the fact that the userbase might actually be growing there is not much real information here. If a site had 50 us

Until the y-axis is normalized to account for the fact that the userbase might actually be growing there is not much real information here. If a site had 50 users a year ago and 5000 users today you would see a similar curve even if all of the earlier users were submitting and commenting ten times as often as they did in the previous year.