Year | Provinces |
2010 | Beijing, Tianjin, Hebei, Shandong, Henan, Anhui, Jiangsu, Shanghai, Hubei |
2012 | Beijing, Tianjin, Hebei, Shandong, Henan, Anhui, Jiangsu, Shanghai |
2014 | Beijing, Tianjin, Hebei, Shandong, Henan, Anhui, Jiangsu, Shanghai |
2016 | Beijing, Tianjin, Hebei, Shandong, Henan, Anhui, Jiangsu, Shanghai |