Nice post! For your "How popular is investing in the community?" section, I would try to adjust that so it's not an absolute number. Right now you don't know whether "investing" seems more popular just because there are more users or stories overall or because a higher proportion of the items submitted are about investing. For example, instead of the raw number of stories that month with "investing" in them, look at something like that number divided by the total number of stories for that month, which would give you the fraction of stories that month that contained the term "investing".