How We Establish Chart Positions
Our charts are a little different to most others in that they measure the popularity of the tracks over a period of time rather than the sales in a particular week. We allocate each track a number of points depending on its weekly Official UK Charts position, the higher the chart position, the greater the number of points. These are then amalgamated to give the total of the points for each month, each year and each decade. This gives a fairer indication of the relative popularity and longevity of songs
Since 2012, we have derived our charts from the weekly top 100 Official UK Chart figures, but for earlier years, we have used either a top 75, top 50, or top 30. For the very early years, only a top 12 was published. Currently, each week we allocate 100 points for a number 1 position, 99 points for number 2 and so on. For those earlier years where weekly top 30, top 50 or top 75 charts were used, a number 1 record would receive 30, 50 or 75 points respectively.
For those years where a top 30, 50 or 75 was used, these were the only charts available to us at the time. Some of these weekly charts had figures for the higher positions which are now available to us, so we are currently updating our database to include all of the tracks which did not make it into the top 30, 50 or 75 and we will then reallocate points and recalculate the annual charts for those earlier years, which may result in some slight changes in positions. At the conclusion of this exercise, every year will have the same methodology of points allocation as mentioned in the previous paragraph, i.e. a number 1 position is allocated 100 points, a number 2 gets 99 points and so on. Even if there are fewer than 100 positions in these older charts, for consitency, we will still allocate 100 points to a number 1 and so on.