It is increasing, a lot. There was a recent study that had OTA using households increase from 9% in 2013 to 15% in 2016. Or as one headline put it "almost double".

Added: Here are some numbers not from memory:

* http://www.ooyala.com/videomind/blog/ota-usage-growing-more-...

Added2: OK I found my numbers, which were slightly off. Fixed...

* http://www.providencejournal.com/news/20170127/tv-antenna-ri...