Q: Most pop songs use the same I-V-vi-IV chord progression -
A: actually more songs use 4, 6-, 1, 5 (same thing but different order) at least from about 1990-2015, but that trend may be starting to fade. for a long time the blues was most popular. but still these have never actually amounted to 'most music.' a 'plurality' possibly but not a 'majority' sorry for the statistics terminology