Using actual USPSA score data from 2016 Limited Nats (October 2016), there were 26 listed shooting minor out of 294 entries (8.84%). The highest of them was 63rd (70% score), then 83rd, then 128th and downward. The 2016 Limited Nats equipment survey had 90% shooting 40sw, 9% 9mm, and 1% 45 ACP. 63% shot 180 gr bullets and another 15% shot 200gr.
Can't really see how Major is falling out of favor in the sport, overall. It'll be interesting to see if there are any "major" changes this year (Iron Sight Nats, in September).