According to latest number from RIAA, music sales in the first half of the year were up 8.4 percent, to $3.4 billion -- the best performance the music industry has seen since its peak days back in the CD era. Recode adds: That boom is fueled entirely by the growth of paid subscription services. This year's numbers include Apple Music, which didn't exist a year ago but has 17 million worldwide subscribers today, as well as Spotify, which has been growing faster than Apple and has 40 million global subs. Digital downloads via stores like iTunes, meanwhile, are falling behind. Those sales dropped 17 percent to $1 billion. And some people still buy CDs, but soon that business will be a footnote: Those sales dropped 14 percent and now make up just 20 percent of U.S. sales. All good, right? Not according to Cary Sherman, who runs the RIAA, the labels' American trade group. He has a Medium post complaining that YouTube doesn't pay enough for all the music it streams, almost all of which is free.