NEW YORK, Feb. 23 (Xinhua) -- Hong Kong has benefited tremendously from the Chinese mainland's reform and opening-up over the past 40 years, Clement Leung, Hong Kong Commissioner for Economics and Trade Affairs to the United States, has said.

"The Hong Kong economy and Hong Kong people benefit a lot from reform and opening-up. That is because of our close relationship with the Chinese mainland," Leung said at a Spring Festival reception held here on Thursday.

According to the senior official, Hong Kong's GDP grew 3.5 percent in 2017. The unemployment rate in the Special Administrative Region is only 2.9 percent, hitting its lowest point in the last 20 years.

The commissioner also highlighted the important role that Hong Kong has played in the process of economic reform and opening-up, saying Hong Kong is still the number one investor in the Chinese mainland.

When talking about the upcoming "two sessions," the annual meetings of China's top legislature and top political advisory body, Leung said one of the main focuses of the Hong Kong delegation to Beijing is to consult with the central government to take more measures to facilitate flows in people, goods, capital and information.

Leung believes that the "two sessions" will help Hong Kong figure out the next role to play in China's development.

China launched its reform and opening-up policy in 1978. From 1979 to 2012, the Chinese economy grew at an average annual rate of 9.8 percent while global growth averaged 2.8 percent in the same period.

After 2012, the country showed greater tolerance for lower growth rates in pursuit of more quality growth and efficiency. China lowered its annual GDP growth target from 7.5 percent in the period 2012-2014 to 6.5 percent last year. Still, China's GDP expanded 6.9 percent in 2017, its first pick up in growth in seven years.