Simplify the following text for a Grade 8 native English-speaking person.
Original: The Australian dollar is currently the fifth-most-traded currency in the world foreign exchange markets behind the US dollar , the euro , the yen and the pound sterling .
Simplified: In 2007 the Australian dollar was the sixth-most-traded currency in world . The most traded currencies were the Euro , US dollar , the yen , the pound sterling , and the Swiss franc .