The album charts were largely a guessing game and could be manipulated by music insiders. That changed in 1991, when SoundScan began electronically tracking sales by retailers. The labels signed on to the service, and Billboard used the data for its Billboard 200 chart.
It didn’t take long for the industry to realize that albums usually peaked in sales during their first week of release, rather than build up momentum over time, as they had long thought. That discovery changed the marketing strategy at record labels, said Peter Lubin, a former record executive, putting the focus on the weeks leading up to the release.