Hong Kong’s population declined last year for the first time since 2003, the Hong Kong Census and Statistics Department said Thursday.

Hong Kong recorded 7.47 million residents in 2020, a 0.6-percent decrease from 2019, according to the census bureau’s annual population report, released February 18. The number of deaths surpassed the number of births in the city last year, causing a “natural decrease” in population for the first time since 1961. The number of residents who left Hong Kong surpassed the number of people who moved to the city as well, resulting in a “net outflow.”

“A natural decrease of 6,700 was recorded for the first time in 2020, with 43,100 births and 49,800 deaths. Meanwhile, a net outflow of 39,800 persons was recorded during 2020, with an inflow of 10,100 One-way Permit holders and a net outflow of 49,900 other Hong Kong residents,” the report stated.

“Largely due to the border control and quarantine measures in place in Hong Kong and other places around the world, as well as the severe interruption of international travel amidst the COVID-19 [Chinese coronavirus] pandemic, we see a substantial drop in the inflow of people into Hong Kong,” a city government spokesperson said on February 18.

Hong Kong applications for a “certificate of no criminal conviction” – a document typically required to immigrate to most countries – surged by 43 percent year-on-year in 2019 to 33,000, according to the Nikkei Asian Review. The figures for 2020 are not yet available.

China imposed a national security law on Hong Kong in June 2020 that undermined the city’s semi-autonomy, which it had been allowed under the terms of its return to Chinese rule from Britain in 1997. The security law was Beijing’s answer to a year and a half-long protest movement in the city decrying Chinese encroachment on Hong Kong society. The legislation increased Hong Kong border security and caused an overall decrease in immigration to the city from China; the flow of Chinese migrants to Hong Kong has contributed at least 1.5 million residents to the city’s population since 1997.

The national security law likewise forced many Hong Kong residents to flee the city last year, with many heading for Britain. The U.K. announced in late January that it plans to welcome as many as five million Hong Kong residents who choose to leave the city in the coming months.

“[H]olders of British National Overseas passports—which are available to Hong Kong citizens born in the territory before it was handed back to China in 1997—can move with their families to the U.K. on five-year visas. After that period, they can apply for British citizenship. Previously these passport holders could only get six-month British visas,” the Wall Street Journal reported on January 29.