@fsi @aral

I don't think "main" is quite accurate: rather "the biggest", many years in a row.

@fsfe : for more transparency and the concerns raised here, how about publicly stating a precise percentage for any donator above 10%?

I do see that in 2017: https://fsfe.org/donate/thankgnus-2017.en.html and 2018: https://fsfe.org/donate/thankgnus-2018.en.html
Google's donations to FSFE covered no more than 10% of the budget.

This suggests that there are statistical fluctuations of the Google contribution to FSFE oscillating around 10%.