2015 marked the first time in history that current music releases were outsold by "catalogue album sales"—a term that refers to any release that is at least 18 months old. To put this in context, just ten years ago current music sales outpaced catalogue music by over 150 million albums.
That information, reported by Music Business Worldwide, comes from a year-end report by Nielsen, the data company most famous for their SoundScan music-sales statistics that inform the Billboard charts. However, this data pertains solely to albums—either physical or digital—and does not include streaming. So, whether the Nielsen report shows a real declining sales trend for new artists, or merely that we've shifted away from albums entirely (the argument that young people are more inclined to stream rather than purchase music seems plausible), is shocking, though perhaps not entirely unexpected.