Hong Kong is one of the world's leading financial centres. Its highly developed capitalist economy has been ranked the freest in the world by the Index of Economic Freedom for 15 consecutive years. It is an important centre for international finance and trade, with one of the greatest concentration of corporate headquarters in the Asia-Pacific region, and is known as one of the Four Asian Tigers for its high growth rates and rapid development between the 1960s and 1990s. In addition, Hong Kong's gross domestic product, between 1961 and 1997, has grown 180 times larger than the former while per capita GDP rose by 87 times.