Data:
2006: 27
2007: 19
2008: 22
2009: 30
2010: 23
2011: 19
2012: 27
2013: 35
2014: 31
2015: 38
2016: 29
Don’t quite know what to make of this. I’m sort of surprised there’s so much variation! I’d have thought I’d have read less when my kids were infants, or when I was writing my own book, but it seems pretty random. I do see that I’ve been clearly reading more books the last few years than I did in 2012 and before.
Lists, as always, are here (2011 on) and here (2006-2010.)
Quomodocumque 
I’m mainly impressed that you manage to still keep track. I’ve stopped in the last 3-4 years. Not bc i read less, bc I’m exhausted with making lists of what I read.
The current one by the way is Here I am which you should if you haven’t already.
Do you count books that you re-read?
Yes, although I barely reread lately!
Are there books that you don’t count? For example, our book, Madison Food, is probably a one-to-two sessions’ reading max and not likely something that would be listed. Would that explain any of the variation? Does page count explain the difference? Animal Farm and Infinite Jest both count as “1” but they don’t both feel like 1.
I agree with JM that page count is important. There is also substantial difference in words/page due to printing design and other factors such as density of dialogue and length of paragraphs. Some books need to be read and contemplated more slowly than others.
JM, I count everything, but sometimes I forget to put stuff on the list, so if your book isn’t on there, it’s an oversight, because I did read it! I guess I don’t usually put bound volumes of comics on there (e.g. I read Squirrel Girl this year, highly recommended), maybe I should.
No worries! Hope you enjoyed it. As I said, a slim volume is more likely to be overlooked and slim volumes may not cluster in a uniform way.
Would you count The Raj Quartet , for example, as one book or four books?