From GameWatcher: “The vast majority of Sonic IP sales, as much as 95 % come from overseas markets, Business Manager Osamu Ohashi has revealed in an interview on Sega’s careers website.
Although Sonic’s overseas popularity dwarfs that in Japan, the publisher will continue aiming to work towards making the IP a bigger name in its home country and other similar regions.”
Source: N4G PC "95% of Sonic's sales are overseas," According to Sega's Osamu Ohashi