And nobody knows how that’s calculated. If the implementation is done via JS we can assume a good portion of all the browsers usage % is incorrect.

here are some actual metrics from our ecommerce site (US, home remodeling / DIY):

if you look at desktop traffic only:

  Nov 2015: 16.01%
  Nov 2016: 13.27%
  Nov 2017: 10.33%
  Nov 2018:  8.14%

Desktop IE in Nov 2018 was 11.37%, Edge 15.65%, Chrome 52.74% and Safari 11.65%.

if you include mobile traffic (where Firefox is basically non-existent), then Nov 2018 is closer to 3.5%.

talk about bleak :(

The absolute number is not that important, the trend is. That's clear even in Mozilla's own data: https://data.firefox.com/dashboard/user-activity shows they went from 303M monthly active users at the end of Nov. 2017 to 277M this year. This is a serious drop.

Not sure if I trust these metrics

They say: "...widely distributed over thousands of websites." https://netmarketshare.com/methodology

Looking at netmarkshet website and web requests it seems this pulls from gator.io for metrics. Looks like 3k-4k websites have this data which lines up with the previous statment. https://publicwww.com/websites/%22gator.io%22/

He linked to Mozilla’s own public data set though. I think other data sets corroborate decline. The 9% might even be optimistic.

Even greater in the US, from 50M to 40M.