I did first have to figure out which cards were added in 2015. Obviously any card listed as a 2015 card was bought in 2015. I searched my scanned cards for any with 2015 in their name and came up with 327 cards. That was easy.
More difficult was finding the cards from other years that I added in 2015. The Billy, Barney, and Ryno collections grew during the year and few were from 2015. I also added a couple more brands and added to the relic and autograph collection. I wasn't sure how I could find all of them. I had to sit and ponder for a bit.
It eventually came to me that any card I bought in 2015 was also scanned in 2015. So I searched for any files that were created in 2015 and voila. The search brought up 312 cards.
Adding the 327 from 2015 sets and 312 from other years equals 639 cards. I guess the 616 I had come up with was wrong. Oops.
I've got the cards in two tiles. On top are the 2015 cards and below them are the ones from other years. I know that the cards look kinda small, but that's what I had to do to get the tiles to fit in blogger. There are 12 cards per row.
Take a look at my 639 additions from 2015: