In fact everybody included me thought $600+ cards made up 1% of the market but actually it was false. I was very surprised to read latest JPR news on Q1 2016 AIB marketshare, it included segments chart I never seen before cos it never been published.
http://jonpeddie.com/publications/add-in-board-report
Accorded to chart $600+ enthusiast cards shipped rough 1 million unit average that made up about 8% of the market in Q1 2016, that worked out over 80,000 units a week, majority of it are GTX 980 Ti. Q3 2015 was very interesting time with around 2 million enthusiast cards shipped worldwide with GTX 980 Ti sold like very expensive hot luxury cakes.