The U.S. dollar broke above 100 yen on Thursday, posting the highest level against the currency in four years.

In New York, the dollar closed at 100-point-45 yen, up one-point-45 percent from Wednesday. The last time the U.S. dollar closed above 100 yen was on April 14th 2009.

Since Japan introduced the floating exchange rate system in February 1973, the dollar first closed at 308 yen but the rate slipped continuously following Japan’s continuous economic growth. Since April 2009, the dollar-yen rate had remained below 100 yen.