The number of South Koreans living in the capital Seoul is declining sharply, and will continue to drop in the coming decades, according to government data Monday.

Seoul’s total population of native South Koreans reached 9.49 million as of May according to the Ministry of the Interior and Safety, showing an alarming decline.

Seoul has been widely known as a city of 10 million residents. The population of Seoul -- both natives and foreigners included -- first surpassed the 10 million bar in 1988. In 1992, the number of total residents in Seoul peaked at 10.97 million.

However, the native population of South Korea’s most populous city has decreased since 2010, with no sign of a significant rebound.

In 2010, the South Korean population of Seoul stood at 10.3 million. But in 2016, the capital city‘s South Korean population finally fell under 10 million for the first time to reach 9.99 million. Decreases continued in following years, and the figure dropped by some 800,000 in May this year since 2010, the ministry‘s data showed.

The recent slide in the city’s native South Korean population was mainly caused by residents moving out of the capital to new towns surrounding Seoul, according to the government-run think tank Seoul Institute. A recent boost of housing supply in Gyeonggi Province has propelled the outflow of residents from Seoul seeking more affordable and bigger housing, the think tank said. The city’s low fertility rate has also contributed to the slide, it added.

On the other hand, the population of surrounding Gyeonggi Province is increasing rapidly. As of end-May, the population of Gyeonggi Province reached 13.58 million, around 4 million more than that of Seoul.

Previously in 2010, the gap between the populations of Seoul and Gyeonggi Province was at 1.47 million. However, the population of Gyeonggi Province has increased rapidly to reach 11.78 million in 2010. It surpassed 12 million in 2012 and 13 million in 2018.

South Korea’s statistics agency predicted that the population of Seoul will shrink to 7.2 million in 2050 in a worst-case scenario, down by 25.1 percent from 9.6 million in 2020, while the country’s total population would decrease to 47.3 million, down 8.6 percent from 51.8 million in 2020.