Michael Jackson had the best-selling album two years in a row with "Thriller." BSR Agency/Gentle Look via Getty Images Billboard, using data recorded by Nielsen Soundscan/Luminate, tracks each year's best-selling album. Since 2015, streaming has been incorporated into music metrics through the use of album-equivalent units. Many classic albums don't appear on the list, having been outsold by lesser-known records. Each year, one album taps into the hearts and ears of the public on its way to...