Short answer? A lot.

It's easily one of Mariah Carey's most recognisable songs, and it's almost always listed as one of the best Christmas songs ever written - but just how much money does she earn a year off the song?

The fact is that reliable data on the subject is hard to come by.

An article in the Daily Mail in 2015 claimed that Carey's 1994 hit made the singer a total of £376,000 annually. However, Daily Mail's article doesn't mention if this is merely from the UK and Ireland or if it's globally. It also doesn't detail exactly where these figures come from, if they're from radio plays or it's from streams.

Another article, this one from the New York Post, says that over the course of 19 years - from 1994 to 2013 - the song made her a total of $50 million in royalties. When we calculate that out on an annual basis, it's $3.8 million per year. When we exchange that over to British pounds, that comes to £2.9 million per year - way more than the Daily Mail's quoted figures.

It's quite possible that the New York Post's figures were global, which would make sense as the song is only popular in a few markets - namely the UK, the US, Canada, and - of course - here in Ireland. Interestingly, however, the song has never charted at No.1 in Ireland. According to IRMA's figures, the song's original release in 1994 saw its highest placement at No. 3 and stayed in the charts for a total of 28 weeks. On its re-release in 2016, it reached No.5 and charted for only four weeks.

Radio stations generally tend not to release figures on how often particular songs are played, and while 'All I Want For Christmas' might get regular airplay on somewhere like Christmas FM, it wouldn't be played with the same regularity on a national station in Ireland like Today FM or 2FM. Not only that, different labels and different radio stations around the world have different arrangements with regards to royalties, so trying to collate a total annual figure for 'All I Want For Christmas' is simply not possible.

If we consider the YouTube video for 'All I Want For Christmas', there's some money to be made there too. According to a study by Rockonomic, they estimated that a Vevo account roughly generates 0.025 cents per view for the artist. So, if we multiply 0.025 cents to the video's current tally - which is 471,191,401 views - we get a figure of $11,779,785. Again, that's a cumulative figure, not an annual one.

Let's look at Spotify next.

Reliable information on how much Spotify plays per stream is equally hard to come by, but a report by DigitalMusicNews.com claims that Spotify pays out 0.00397 cents per play. Numerous other reports cite this figure, and it's reasonable to assume it's correct. Currently, 'All I Want For Christmas' has 400,146,536 plays as of writing. Again, multiplying 0.00397 by 400,146,536 gives us a figure of $1,558,581 - and 75 cents. Again, keep in mind that that's cumulative figure, not an annual one. In fact, on December 24th of last year, the song hit 10 million streams in one day on Spotify. Again, using the figure of 0.00397 cents, Mariah Carey made $42,951.46 in a single day from the song.

The other part that's left out of almost every report we've managed to dig up is how much money the song makes through licensing as opposed to royalties.

Royalties are pay-per-play basis, meaning whenever it gets airplay, Mariah picks up a cheque. Licensing, on the other hand, is when the song appears in a movie or TV show - and that varies wildly. A quick search on IMDb found that the song has been used a total of 60 times.

Low-end TV usage, meaning something playing in the background or on a jukebox, would cost around $2,000 a pop for five years. For films, it can be around $10,000 in perpetuity. The more popular song, of course, the higher the amount they can charge. If it's for a commercial, you're talking about anything up to and including $500,000 per year. Just to add to the song's popularity, it's been turned into children's novel and a Christmas movie.

So, to answer the question, how much money has Mariah Carey's All I Want For Christmas made? A lot. A LOT.