“Billboard and Nielsen SoundScan, the agency that supplies its data, will start adding streams and downloads of tracks to the formula behind the Billboard 200, which, since 1956 has functioned as the music world’s weekly scorecard. It is the biggest change since 1991, when the magazine began using hard sales data from SoundScan, a revolutionary change in a music industry that had long based its charts on highly fudgeable surveys of record stores.”