BEIJING, Nov. 22 (Xinhua) -- The number of permanent residents in Beijing decreased for the first time in two decades, official data showed Thursday.

In 2017, the number of Beijing's permanent residents was 21.707 million, 22,000 fewer than in 2016, according to the Standing Committee of Beijing Municipal People's Congress.

According to a report reviewed by the committee, the number of permanent residents in the city's six urban districts continues to decrease. In 2016 and 2017, Beijing saw a total decline of 740,000 permanent residents in the six districts, down 3 percent year-on-year.

Beijing plans to cap its population as it seeks to address "big city diseases" such as traffic congestion and pollution.