Hong Kong was rated the world's freest economy for the 17th straight year in a ranking by the US-based Heritage Foundation, above rivals Singapore and Australia for the title.

Hong Kong, with a score of 89.7, is well above the world average of 59.7, the Washington-based Heritage Foundation said in its 2011 Index of Economic Freedom report released Wednesday.

The study assesses 183 economies, out of which the Chinese mainland ranks 135th.

"Hong Kong, one of the world's most competitive financial and business centers, demonstrated a high degree of resilience during the global financial crisis," the report said.

Freedom in trade and finance was the biggest boost to Hong Kong's ranking, while investment freedom and property rights, business and monetary freedom all scored highly.

The United States fell to 9th from 8th last year and the UK slipped to the 16th place from 11th in 2010 it added. North Korea ranked 179th, at the bottom of the list with a score of 1.0.