Catalogue albums, or more commonly called old music, have outsold modern music by 4.3 million copies, according to a report. This is the first time in history that this phenomenon happened.

Citing a Nielsen year-end sales study of the music industry, the report said that catalogue album sales - those containing 'old' music released more than 18 months ago, are outpacing current music releases.

About ten years ago, current music album sales outsold catalogue music by more than 150 million. Now, the latter has outpaced the former by over 4.3 million copies.

Nielsen is the data company that is famous for its SoundScan music-sales statistics that Billboard uses in its charts. But it should be noted that this data is only referring to the albums sold last year and does not include music sold through online streaming.

Nevertheless, the figures show that catalogue music seems to be experiencing a renaissance.

In the area of digital sales, current albums still have a slight edge. However, in terms of physical releases, it seems more people chose to buy the oldies. Even with regards to individual tracks, the figures show that catalogue music outsold modern digitals as well.

Another report tries to offer some theories on how this came about.

This report surmises that it is because of the so-called vinyl revival. Sales of vinyl records have considerably jumped in recent years, owing to the younger set discovering olden LP vinyl records.

Vinyl record sales rose to 52 percent in the first half of 2015. If a person is collecting a vinyl album set, it stands to reason that he will look for vinyl records and not get it from digital online sources.

This theory seems possible because, based on the figures reported by Nielsen, "Dark Side of the Moon," by Pink Floyd, earns the distinction of being the third highest selling album of 2015 - all in vinyl form, not digital.