The website w3schools posts time series data of its visitors’ browsers and operating systems (OS). Because the site is relatively popular and unbiased in terms of its visitors’ software, the trends gleaned from their data are likely representative of the internet-using population as a whole. Several other websites post data like this (e.g., http://gs.statcounter.com), so if you want to learn more or make a comparison, there are additional resources.
I’ve plotted area charts of both the browser and OS data. The browser data are binned to show both the market share (as a percentage of users) of a given browser, as well as the patterns in how frequently users update to the latest version of the software. Note that Internet Explorer updates are released much less frequently; Chrome and Firefox both have patches released every couple months.
The OS data show that, despite a recent increase in the market share for Mac (non-mobile Apple products), various versions of Windows are still the dominant global OS.