Mac OS not gaining steam?

The Mac OS isn't growing like crazy, despite the increased number of classmates, professors and coworkers working from their Macs.  I'm surprised.  It's been about even over the last year.  Maybe part of this can be explained by the emergence of iOS on iPads and Android on other tablets.  Windows has been steadily declining and now occupies about 89% of the market share.  Linux is on the decline too.