I'm having the same issue. On a hunch, I checked the details for one of my zones, Shp: United States: 48, which came with MZMT. I ran the SQL, and it affected 49 rows, but only one state, Alabama, shows when I look at the details of the zone in admin. I suspect that you might have the same problem. Check the details on your 'Rest of the World' doesn't include Peru, as I suspect it will be why you're getting the higher rate.

I'm going to look at the SQL code for my area, and see if I can fix it, as adding each state by hand is a bit laborious.