Found the highest Amazon rank I've attained so far...

June 13, 2014 I was 39,950 th in text book sales on Amazon.

That's about a 400th of the Top 100 Authors.

My amazon page may be found at: http://www.amazon.com/author/nathancoppedge

Buying gift cards with the intend of buying Nathan Coppedge books is a good idea, because I produce books every year on interesting subjects (there are already over 70 titles to choose from!)

My earnings as an author...

2012

$16.16

2013

$43

2014

$269.99, some of it unpaid in that year ($85.27 subtracted out because it was not earned yet).

2015

$254.66 earned by Oct. 21st.

Total:

Almost $500.

(But note also that I'm trying to dig myself out of the money I spent on Authorhouse, which was probably at least $1200. So, technically I'm still in the hole). My current publisher (Amazon/ CreateSpace) is the only reason I have any earnings potential, besides the content of my books.

The above includes both texts and e-books.

Notice, the exponential curve has dropped off.  I suspect this is because of poor marketing from my publisher.

But, at least the year has not been worse than last, if I assume some continued sales in Nov - Dec.

My author page may be found at: http://www.amazon.com/author/nathancoppedge 
notably I have not sold copies of The Structure of Philosophical Revolutions yet (It's been about a week or two).