Taiwan's Central Bank of China was the country's most profitable financial institution in 2005, with profits of TWD187.7 billion. CBC attributed the profits mainly to gains from transactions of its foreign exchange reserves, and from interest generated by deposits in foreign banks. Last year CBC's forex reserves ranged between US$242.7 billion US$253.2 billion, which accounted for 95% of the banks total assets. The interest paid on the reserve deposits averaged at about US$800 million per month. Last year, CBC earned revenue of TWD324.8 billion, while incurring expenditure of TWD154.2 billion to realize profits of TWD187.7 billion for the year, equivalent to a 4% return on investment.