Music streaming continues to provide a big boost to music industry revenue. In fact, digital music now outsells physical formats worldwide, nabbing 45 percent of all purchases in 2015 according to IFPI's Global Music Report. If you'll recall, the RIAA reported last March that music streaming had overtaken physical sales in the US, and the trend continued worldwide last year. Digital revenue accounted for $6.7 billion, thanks largely to a 45-percent increase in what streaming services took in. Despite industry revenue growth of 3.2 percent or $15 million for 2015, both physical sales and digital downloads declined.