Oh that's a good question.
I did some math.
Edit: missed a few non-Switch games! Added below, and percentage recalculated.
Games:
Switch - 27 games
PS4 - 16 games
XOne - 13 games
PSV - 4 games
3DS - 4 games
PS3 - 3 games
Xbox - 1 game
SNES - 1 game
I'd say about 250 hours of gaming across those Switch games, with BotW taking up about 36% of that. I'd guess I spent about 400 hours across the other platforms. So I spent roughly 38% of the last year playing Switch.
This was fun :)