In 2023, it was 75% of their revenue that came from Google.

https://assets.mozilla.net/annualreport/2024/mozilla-fdn-202...

  2023: 75.8
  2022: 86.0
  2021: 87.8
  2020: 88.8
  2019: [^a]
  2018: 95.3
  2017: 95.9

[^a]: this was a weird year where their "other" income got a massive one-time boost. I'm not sure what happened. Did they get a $338m grant? If you take that number out (which is normally at or near zero) the percentage is around 91%