According to https://gs.statcounter.com/browser-version-market-share (see the CSV for unabridged data), Chrome 49, 61, and 63 seem to be oddly popular today, given their age.
- Chrome 49: 2016-03-02
- Chrome 61: 2017-09-05
- Chrome 63: 2017-12-05
Yet these three browsers all have greater marketshare than Chrome 72 and 73 (from early this year). Chrome 49 and 63 seem to be slowly declining, but Chrome 61 actually increased over the first half of 2019 (from 0.07% in Jan to 0.47% in July).
Are there operating systems that ship with these specific versions? Organizations that haven't upgraded? Or are other browsers (or bots) using these user agent strings?
Extra thanks if you can also tell me why Safari 5.1 has 0.77% market share. Are that many people still running Snow Leopard?