Google Trends on VR search queries: https://trends.google.com/trends/explore?q=vr,psvr,%2Fm%2F0k...
(interesting here is the decline after the peak)
Same query again but with 'iphone' this time (to represent the mobile space and its size compared to VR): https://trends.google.com/trends/explore?q=vr,psvr,%2Fm%2F0k...