It’s the time of year when our thoughts inevitably turn to ways of producing a topical graph that looks like a Christmas tree.

Here is a graph of the positions of Christmas songs in the UK Top 100 singles charts during the 1990s. Christmas songs are defined as those with the word ‘Christmas’ in the title, and each week I have added up the scores for all of the Christmas songs, giving 100 points to the #1 single, down to one point for the song at #100 in the chart. I’ve then plotted the total score according to the time (in weeks) before or after Christmas Day, and coloured them according to year (January and February are allocated to the Christmas of the previous calendar year). The area under the curve for each year is coloured a translucent green.

Not surprisingly, Christmas singles tend to peak in the week or so before Christmas. They typically enter the chart about four weeks before Christmas Day, and leave around four weeks after.

There were 37 such Christmas songs in the UK Top 100 during the 1990s, spending a total of 149 weeks in the charts. The peak year, 1995 (the top point of our chart above) had seven of them in the chart a week before Christmas, none higher than 10th place.

Of course, this analysis could be improved. Plenty of Christmas songs don’t have the word ‘Christmas’ in the title, for example. The system of points I have used probably does not reflect actual sales very well. And the 1990s might not be typical (but I happened to have the data available).

But never mind all that – the most important thing is that the chart looks a bit like a Christmas tree. Merry Christmas!