In windows, it's a fairly common experience to stumble on an app with a horizontal scrollbar and be forced to click and drag the scrollbar (terrible UX), where as in most Mac devices you can simply swipe to the side. Some trackpads/mice simply do not offer side-swiping.
How common is side-swiping in Windows machines in 2015? All MacBooks, Magic trackpads, and Magic Mice do it natively. Is it safe to assume that the gesture will be ubiquitous in Windows machines by 2017?
Related answer on how to deal with the differences: How do Windows users interact with scrolling panes? I'm interested in the actual statistics rather than possible solutions.