I just wanted to make the point that you can't really do a comparison of the numbers that ranked up yet as it takes 8.5 months to get the activity to get from Sr. to Hero we'll have to wait that long to get a fair measure.
To get a true picture, you would also need to include a breakdown for primary areas of interest. We have some members who are only active in certain areas such as technical, legal or speculation/statistics. I think they are valuable members of the community, but they are unlikely to increase rank at the same rate as members with more general interests. We also have the spammers, and alt promoters, and their 'nepotism' will allow them to remove ranking barriers at a faster rate than more worthy members.