New York (AFP) - Twenty One Pilots has reached a milestone -- every song on the pop-rap duo's last album, "Blurryface," has been certified as selling gold or platinum.

The Ohio musicians, who blend hip-hop with light rock, scored their biggest success yet with the 2015 album, especially "Stressed Out," a nostalgic song about yearning for childhood stability.

The Recording Industry Association of America said Thursday that all 14 songs on "Blurryface" had been certified gold, which means sales of 500,000 in the United States, or platinum, which is one million.

The feat was believed to be the first ever. The industry group said it verified that no other album had all songs certified gold or platinum at least since the start of the digital music era, when comparable data became available.

The association since 2016 has been factoring streaming into its sales data, giving an added boost to songs that may have been overlooked in earlier times as obscurities only heard by fans who bought the album.

Streaming and digital downloading platforms such as iTunes allow listeners to choose any song instantly, not just the singles which labels pick to promote.

"Blurryface" as an album has been certified three-times multi-platinum, meaning it sold three million copies.