Mint is hardly a minor Linux distro - it has the biggest number of hits on Distrowatch, 3724 against Ubuntu’s 2240!
I wouldn't trust Distrowatch's numbers.... I think there's very little doubt that Ubuntu trumps Mint on adoption..... Ubuntu has all the business server and desktop users to start with that Mint doesn't, before you add on their home user base with is almost certainly larger than Mint's.