Simplify the following text for a Grade 8 native English-speaking person.
Original: The New Taiwan dollar ( currency code TWD and common abbreviation NT$ ) , or simply Taiwan dollar , is the official currency of the Taiwan Area of the Republic of China ( ROC ) since 1949 , when it replaced the Old Taiwan dollar .
Simplified: The New Taiwan dollar ( currency code TWD and common abbreviation NT$ ) , or simply Taiwan dollar , is the official currency of Taiwan . It was used since 1949 , when it replaced the Old Taiwan dollar .