Beijing in 2018 enjoyed the most blue skies in the last four years, as shown in photos released Friday by weather.com.cn, a public service website run by the China Meteorological Administration.

Skies in 2018 photographed by residents in Beijing. (File Photo: Weather.com.cn)

The photos show that the number of blue skies in Beijing in 2018 increased 3 percent compared to 2017, and other major cities such as Chongqing, Zhengzhou, Shenyang and Nanjing also had more blue skies in 2018 compared to 2017.

The photos of skies come from residents in 15 cities in China who participated in a program called “National Blue Sky Photographer” with weather.com.cn.

Blue skies were seen in more than 70 percent of the days in 2018 in Hohhot, north China's Inner Mongolia Autonomous Region. Other northern cities such as Shenyang, Liaoning Province, and Qingdao, Shandong Province, also enjoyed blue skies for over half of the days in the year.

Southern cities such as Chongqing and Guangzhou, Guangdong Province, had blue skies for less than 40 percent of the days in the year, but high air quality for over 80 percent of the days, due to frequent rain.