The Hong Kong dollar is officially linked to the US dollar at the rate of 7.8 Hong Kong dollars to one US dollar. Under this linked exchange rate system, the Government undertakes to back the entire monetary base of Hong Kong with US dollars. The linked exchange rate is the cornerstone of Hong Kong's monetary system. It plays an important part in supporting Hong Kong's role as a trading, service and financial centre. Throughout most of its history as a trading centre, Hong Kong has had a linked exchange rate system of one form or another. The main exception came during the nine years of a floating exchange rate regime between 1974 and 1983. The experience with a free floating Hong Kong dollar was difficult and unstable. In October 1983, at a time of financial crisis and political uncertainty about Hong Kong's future, the Hong Kong Government announced the decision to link the Hong Kong dollar to the US dollar at a fixed exchange rate of 7.8 Hong Kong dollars to 1 US dollar. Sir John Bremridge, Financial Secretary from 1981 to 1986: "It is our intention to hold this rate unchanged."