The article's ADI charts do not account for Mozilla moving Windows XP and Vista users from the Firefox release channel to the ESR (Extended Support Release) cha

The article's ADI charts do not account for Mozilla moving Windows XP and Vista users from the Firefox release channel to the ESR (Extended Support Release) channel in March 2017 [1]. New versions of Firefox do not support XP or Vista, but XP and Vista users will continue to receive ESR security updates at least through 2018 Q1. You can see a similar "drop" in Mozilla's Firefox Hardware Report [2]. [1] https://blog.mozilla.org/futurereleases/2016/12/23/firefox-support-for-xp-and-vista/ https://blog.mozilla.org/futurereleases/2016/12/23/firefox-s... [2] https://hardware.metrics.mozilla.com/ https://hardware.metrics.mozilla.com/