I'm pretty sure 1:3 is far, far above the real amount.

I did a little searching and came up with this http://hobby.rin.ru/eng/articles/html/306.html

About hepatitis: Of the 13,387 annual cases of hepatitis detailed in the most recent CDC report, 12 are associated with tattoo studios. By comparison, 43 cases -- or better than 300% more -- are associated with dental offices.

Note that there are about 15,000 tatoo studios in the US.