I'm interested to know how you are determining these ranks. I just tried a bunch of keywords that I focus on for certain sites, and have focused on for a couple of years. I know these are difficult keywords yet all but a handful turn up 0 days, 0 sites are indexed.

SEOMoz has a keyword difficulty tool (http://www.seomoz.org/keyword-difficulty/). I've never looked in to the methodology they use but it seems fairly accurate in its difficulty measure.