Here is a list of most popular switch games made by Nintendo....
Tears of the kingdom
Mario Kart 8 Deluxe
Super Mario Odyssey
Super Smash Bros. Ultimate
Breath of the Wild
Metroid Dread Initial
Super Mario Bros. Wonder
Mario Party Superstars
Splatoon 3 Initial release date:
Kirby and the Forgotten Land
Pikmin 4 Initial
Pokémon Legends:
Nintendo Switch Sports
Pokémon Sword and Shield
Pokemon Scarlet
Super Mario 3d World
Animal Crossing
Splatoon 2
Zelda Links Awakening
Super Mario Maker 2
Super Mario Bros U Deluxe
Princess peach showtime
Mario vs Donkey Kong
Arms
Captain Toad Tressur Tracker
Ring fit Adventure
Skyward Sword HD
Mario 3d All Stars
Ok but out of these, new for switch (not regurgitated from Wii U or further) worth buying, the list gets way, way smaller:
Tears of the kingdom
Super Mario Odyssey
Breath of the Wild
Metroid Dread Initial
Super Mario Bros. Wonder
Kirby and the Forgotten Land
Admitedly the list is larger for some, but these at the heavy hitter AAA games.
It's been over 7 years since the switch launched.....so lets add back in a pokemon game or pikmin and you have your one per year. Also most numbers flush this out, the average switch owner buys betweeen 7 and 8 games.
Obviously which titles they buy will vary somewhat.