In 1955 on this day Decca Records (remember them?) announced that Billey Hailey had sold More than 3 million records, in just 13 months.

These days, when new sensation follows new sensation, it would be unusual for the sale of a single to continue for so long, or to sell so many copies.  Formats have changed of course.  LPs were not the format of choice then being more aimed at jazz and classical music rather than pop.  That did not really change until the 60s.