I got my first ereader, a Sony, in 2009 so I've just passed my four year anniversary last month for owning a dedicated reader. First Kindle in Sept. 2010 (so it's coming up for three years in about 3 months time) and a quick check of my library there say it's 15 pages long with a total of 285 items in it.
We (my Mother and I) have a total of 4 Kindles altogether. My favourite is still the original Keyboard Kindle I bought in 2010.
I bought a lot of Kindle books in my first year or so, not so much since, but its still a heck of a lot of books.

Luckily not all mine ... and quite a few of the titles were freebies.