Passage: The Qingming Festival has been observed by the Chinese for over 2500 years. It became a public holiday in mainland China in 2008. In Taiwan, the public holiday was in the past observed on 5 April to honor the death of Chiang Kai-shek on that day in 1975, but with Chiang's popularity waning, this convention is not being observed. A similar holiday is observed in the Ryukyu Islands, called Shīmī in the local language.

Question: When did the Qingming festival become a public holiday in mainland China?
2008