The minute Halloween gets over, the streaming numbers for Mariah Carey’s hit single “All I Want for Christmas Is You” shoots up in the streaming charts. On December 16 of this year, the iconic Christmas song finally reached the top spot on the Billboard Hot 100 chart.

According to a 2017 report in the Economist, the song has made Carey richer by 60 million dollars in royalties since it released. In Amazon Music’s recent documentary, the songstress declared that the song was a “happy accident”. She goes on to say that she started writing the song when she was living in upstate New York.

“Actually, I put on [the movie] ‘It’s A Wonderful Life’ downstairs. You could hear it throughout the house,” Carey said in the documentary. A self-described “terrible piano player,” she says.

Adding that she stumbled upon the melody and chord progression, she goes on to state that: “It was done very quickly and kind of came out organically, which the best songs do.”

Co-writer of the song, Walter Afanasieff said that it’s true that the song was written in an hour and then a week or two was spent in sharpening the lyrics. In fact, the song very nearly never saw the light of day. According to CNBC, Carey wasn’t sure that an original Christmas song would resonate with audiences.

“I didn’t feel, from a strategic point of view, that it was time to do something like that,” Carey told EW in a recent interview. “As much as I love Christmas, I thought that the record company was off. Obviously, I couldn’t have been more wrong.”

Now, the singer considers the song to be one of her greatest achievements.

In the United States, “All I Want for Christmas Is You” is the highest-selling holiday digital song with 3.6 million downloads purchased, reports Billboard.