Most popular instrumental sub-genre?

[cuallito]

I was wondering if anyone could tell me what the most popular instrumental sub-genre is on Spotify? (I know there are over 1000 subgenres in Spotify, so even they might not have the data.)

I mean subgenres where the focus is on the music being played, not on the lyrics being sung, so prog rock, classical, trance, some kinds of metal  etc. NOT pop or singer-songwriter, for example.

My guess would be prog-rock?

Thanks.