Income from online streaming services like Spotify, Pandora and YouTube is growing rapidly, but not enough to lift the music industry into growth over all, the industry’s global trade group reported on Tuesday.

According to an annual sales report from the trade group, the International Federation of the Phonographic Industry, wholesale revenue from recorded music around the world in 2013 fell by 3.9 percent compared with the year before, to $15 billion.

Beneath that number, however, is a complex picture that shows how the recorded music business is trying to reverse its fortunes, which have been slipping since a peak of $27.6 billion in 1999, according to the trade group, which is based in London.

Digital sales last year grew by 4.3 percent around the world, led by a 51 percent increase in revenue from subscription services. Income from these all-you-can-listen outlets, like Spotify, Deezer and Rhapsody, exceeded $1 billion for the first time last year, the federation said. About 28 million people around the world pay for access to them, up from eight million just three years earlier.