As of December 31st, 2017, The Legend of Zelda: Breath of the Wild has outsold every Zelda game globally with the exception of The Legend of Zelda: Twilight Princess.
As part of their financial results briefing earlier today, Nintendo reported that Breath of the Wild has shipped 6.7 million units worldwide on the Nintendo Switch.
READ HERE IMPORTANT
With nintendo announcing sell through as in to "customers", botw switch is 6mil by years end (700k on store shelves)
They made it clear sold to consumers botw including wiiu version is 7.5mil (so wiiu botw sold through 1.5mil)
Here is the breakdown
6.7mil BotW NSW (6mil sold thru)
1.5mil+ BotW WiiU (1.5mil sold thru)
8.2mil+ NSW+WiiU (7.5mil sold thru)
More info! TP sold 8.85mil lifetime, botw needs to ship around 650k more to beat it lifetime (1.8mil for 10mil goal)