The United States Dollar (USD) is the official currency of the United States, first issued in 1792. It is identified by the ISO 4217 code USD and is commonly represented by the symbol $. The authority for issuing US dollars lies with the United States Department of the Treasury. Currently, circulating US dollar banknotes include denominations of 1, 2, 5, 10, 20, 50, and 100 dollars, along with coins in denominations of 1, 5, 10, 25, 50 cents, and 1 dollar. The U.S. Dollar ranks first globally in terms of trading volume, comprising 88.3% of the total global foreign exchange transactions. Local money changers in Hong Kong all offer the buying and selling of U.S. Dollars.