According to the Windows lifecycle fact sheet, Windows 7 mainstream support ended in January 13, 2015 and extended support will end in January 14, 2020.
Many hospitals are running Windows 7. They jumped from Windows XP to Windows 7, even when Windows 8 was available. Remember that Windows 10 was released in July, 2015. Given that changing operating systems across an entire hospital enterprise is considerable work, I would not be surprised if many hospitals remain on Windows 7 through 2019. After all, 2019 is only 3 years away.
I've personally really enjoyed using Windows 10 and the operating system offers the right balance of functionality when I'm using my mobile PC as a laptop/desktop vs. a touch-screen tablet. Now that I've become so accustomed to Windows 10, it's hard to go back to any mobile device running Windows 8.