Add a total usage count column to the Song Usage report

The Song Usage report in Planning shows, for a selected period, when each song was used and on which dates. This is helpful, but it would be even better to have one more column next to each song: a simple counter showing the total number of times that song was used during the selected period.
Right now we can see the individual dates, but there's no at-a-glance total. When exporting, each song comes out separately, and when printing we get the same layout as on the site — so a summary count per song would make it much quicker to see which songs are used most (or least) over a given period, both on screen and in the printed/exported version.