Total iCloud storage used does not add up?

Hello,

I noticed today that I'm nearing the end of my 200GB storage plan, so I thought I'd look into why. It says I have about 14GB free. The breakdown listed on iCloud.com is as follows: Photos and Videos - 106GB, Backups - 72GB, Documents - 9GB, Mail - 1GB. The problem is that on all my devices, the BACKUPS segment should only be taking up about 11GB because I only have two phone backups on there (9GB and 2GB).

My questions is why does it say I'm using 72GB for Backups when I've only got 11 total GB of backup data?