You are absolutely right Dom. MS researcher are kind of like TV weather announcers. They always leave enough of a "fudge factor" that it's impossible to ever prove them wrong.
I typed "ms incidence" into google and the first site (wrongdiagnosis.com) mentioned 1/700, which doesn't do me a lot of good because math isn't my forte. I am sometimes able to count all the way to 21...when I'm willing to risk arrest for public indecency.....again.
The next site (neurologychannel.com) quoted "northern United States have the highest prevalence, with more than 30 cases per 100,000 people."
Most sources estimate that there are around 400,000 cases of MS in the US and the population of the US is about.......a whole bunch. A whole bunch divided by 400,000 is just about 91.7 per 100,000 exactly.....if my math is correct