Oh great - another number to obsess over.
I saw the rank thingy yesterday when I went to check my amazon author profile for something else.
I actually have a fairly good (or did this morning) in the religion and spirituality breakdown.
That being said, most of my book sales are not on amazon or even in brick and mortar book stores. The majority of my books are old through specialty shops, and their sales number are not counted by amazon or the (I am drawing a blank on a name) other sales recording outlet.
I think the only number that really matters is the one following the dollar sign on our royalty checks. Seriously, those numbers are ones that affect my bottom line. amazon is a bully playing the popularity game of a jr. high girl. I never won those as a kid, I was too weird even then to rise to the most popular in anything.