These all-time rankings are based on actual performance on the weekly Billboard Hot 100 (from its launch on Aug. 4, 1958 through Oct. 10, 2015) and Billboard 200 (from Aug. 17, 1963 — when we combined our two leading pop album album charts for stereo and mono releases into one all-encompassing weekly chart — through Oct. 10, 2015). Titles are ranked based on an inverse point system, with weeks at No. 1 earning the greatest value and weeks at lower rungs earning the least. Due to changes in chart methodology over the years, eras are weighted differently to account for chart turnover rates over various periods. Artists are ranked based on the combined point totals, as outlined above, of all their Hot 100 or Billboard 200 chart entries.