This is not when you bought what games in what year, this is what games do you own that are from which year, if that makes any sense. 

Example, I bought Warriors Orochi 3 Hyper in 2015, but since it was a launch title, it goes in the 2012 section.

2012 

I have 7 from 2012 - Warriors Orochi 3 Hyper, Mass Effect 3, Darksiders II, Assassin's Creed III, Tekken Tag Tournament 2, Nintendoland and ZombiU

2013

I have 8 from 2013 - (technically 9 because Pikmin 3 is on its way) Monster Hunter 3 Ultimate, The Wonderful 101, Lego City Undercover, Super Mario 3D World, Need for Speed Most Wanted U, Wii Sports Club, Assassin's Creed IV: Black Flag, Windwaker HD (digital)

2014 

I have 6 from 2014 - Mario Kart 8, Hyrule Warriors, Bayonetta 2, Super Smash Bros 4, Watch_Dogs, Captain Toad: Treasure Tracker and Donkey Kong Country: Tropical Freeze.

2015 (Slowing down because I was trying to get though backlog and I started getting more games for other systems, I still plan to buy a few more 2015 releases)

I have 4 from 2015 - Splatoon, Legend of Kay Anniversary, Xenoblade Chronicles X and Rodea The Sky Soldier

2016

I have 1 from 2016 - Twilight Princess HD (almost 2 cause Pokken is releasing soon)

2012 - 1 Nintendo Land
2013 - 1 The Wind Waker HD
2014 - 1 Super Smash Bros 4 Wii U
2015 - 1 Splatoon

Is about 1 per year!

But I've played a lot more than this! :p

Edit: Forgot to include Digital though..

Counting only ones I still own and only retail/downloadable retail games

2013 - 0 *cri* R.I.P. Wind Waker HD *cri*

2014 - 7

Mario Kart 8
Pikmin 3
Hyrule Warriors
New Super Mario Bros. U
Super Smash Bros. for Wii U
Super Mario 3D World
Captain Toad: Treasure Tracker

2015 - 5

DKC: Tropical Freeze
Splatoon
Super Mario Maker
Yoshi's Woolly World
Xenoblade Chronicles X

2016 - 1

Zelda: Twilight Princess HD

Right... let me think about this.

2013: Nintendo Land, Batman: AC, Darksiders II, Wind Waker HD, Assassin's Creed III;

2014: Super Mario 3D World, Mario Kart 8, (MH3U), Splinter Cell Blacklist, Deus Ex: Human Revolution;

2015: Super Smash Bros. U, Hyrule Warriors, Mario Maker, Mario Tennis Ultra Smash;

2016: Bayonetta 2;

Eh, I guess you could say roughly 4 games a year.

2012: 3 (Nintendo Land, Mario Bros. U and ZombiU)
2013: 4 (Wind Waker HD, Super Luigi U, Pikmin 3 and Mario 3D World)
2014: 6 (Bayonetta 1 and 2, Donkey Kong Tropical Freeze, Hyrule Warriors, Mario Kart 8 and Smash Bros.)
2015: 0 (will buy Mario Maker, Wooly World and maybe Kirby someday)
2016: 0 (will buy Twilight Princess HD when I start my summer job in May)

2013- Super Mario 3d World, Madden 13, NSMU
2014- Batman Arkham Origins, Mario Kart 8, Smash Bros, Bayonetta 2
2015- Splatoon, Minecraft, Yoshi Wolly World, Fast Racing Neo
2016- Xenoblade X, Zelda TPP

Im probably missing a few game si cant remember at this time. 

Tagged. Getting my receipts...

I don't know the exact numbers but I've had it for 3 years and I have 22 games, so roughly 7-8 games a year.  For reference I've had my PS4 for a little under a year and have 29 games.  That really puts in perspective the Wii U's lack of games.  

2013: Pikmin 3, Rayman Legends, Wind Waker HD, Super Mario 3D World
2014: Tropical Freeze, Child of Light, Mario Kart 8, Hyrule Warriors, Bayonetta 1 & 2, Super Smash Bros, Captain Toad
2015: Splatoon, Super Mario Maker, Yoshi's Woolly World
2016: None, but I will most likely own TP HD and Pokken by the end of the week

Bought my Wii U on April 2014

2014 - 8
New Super Mario Bros. U + Luigi (Came with the console)
Super Mario 3D World
Wind Waker HD
Mario Kart 8
Bayonetta 2
Scribblenauts Unlimited
Super Smash Bros.
Donkey Kong Tropical Freeze (Don't own anymore)

2015 - 1
Splatoon

2016 - 0
None so far. It will probably stay that way if Zelda comes to NX =P