In the United Kingdom and Ireland, there is a tradition that the song that reaches number one in the chart the week before Christmas (or on Christmas Day itself if Christmas falls on the day in which the chart is published) is that years Christmas number one. Traditionally, this was the strongest chart week, where several big artists would release songs, but in recent years both UK and Ireland have had the most recent X Factor winner as the Christmas Number One.
In the UK it is most likely that the winner of this years X factor will once again take Christmas Number One, the 2014 version of Band Aid's "Do they know it's Christmas?" was considered a contender after gaining Christmas Number One with all three previous versions, but it has already fallen to number two this week. This will be the first time streaming has been including in the UK chart for a Christmas number one, so that could have an impact as well.
I know this not a tradition in any other Eurovision Countries, and that many countries do not even celebrate Christmas, but I thought it would be fascinating to see what gets to Christmas Number One around the world!