I don't think we should do this, but for fun here's a StackQL query to help see where the "80/20" rule really is:
http://stackql.net/default.aspx?qid=7020
Looks like the top 10 users have nearly 2.5 percent of the total rep.
Edit — updated the link, looks like about an 88/12 split (12 percent of users have 88 percent of the rep.) or 84/16 if you exclude users with 1 rep.