NEW YORK (AP) — Measles cases are accelerating, and in the last five months have caused more U.S. illnesses than in any entire year since 1996.Health officials say 307 cases have been reported since New Year’s Day. About half have been in the past month — most from a huge outbreak in unvaccinated Amish communities in Ohio.That’s a blistering start, even before the customary spurt of cases seen in the late spring and summer, health officials noted.“Measles has reached a 20-year high. This is not the kind of record we want to break,” said Dr. Anne Schuchat of the Centers for Disease Control and Prevention.The CDC released the latest numbers Thursday during a news conference.Nearly all the cases have been linked to travelers who caught the virus abroad and spread it in the United States among unvaccinated people.