One in every five people from overseas who live on the Chinese mainland have settled in Shanghai, while the figure narrows to one in every four for foreigners in the nation's most cosmopolitan metropolis, said a new study released Monday by Shanghai Municipal Statistics Bureau.

More than half of the city's 208,300 residents from overseas live on their own, while just over 20 percent of the demographic have a spouse from the Chinese mainland, said the bureau's study, which broke down categories within the city's overseas population based on data from the nation's latest census last year. It was the first to count people from outside the Chinese mainland, including foreigners and residents from Hong Kong, Taiwan and Macao.

Some 54.2 percent, or 112,900 people comprising Shanghai's overseas population are without family in the city, while 24.3 percent, or 50,617 people have married someone from the Chinese mainland - with 2,231 of the couples tying the knot last year.

The city with the largest overseas population on the Chinese mainland, Shanghai is the place that 112,200 overseas families call home these days, among which roughly a third, or 33.2 percent of them hail from Hong Kong, Taiwan and Macao, said the report.

The average size of an overseas family in Shanghai is 1.86 people per household, 0.64-person less than the average household in the city. Yet, while only 10 percent of overseas families in the city having more than four family members, 20.4 percent of the city's overseas population is below the age of 14.

The study added that overseas people in the city are on average 33.3 years of age, with only 6.1 percent of the demographic above the age of 60.

But, with the average stay in the city for overseas residents settling at 20 months - with people from South Korea, Malaysia, Singapore, UK, France, Germany and Canada, tending to prolong their visit slightly longer - the city must do more to retain overseas talents to further advance Shanghai's development, according to Zhou Haiwang, a population researcher at Shanghai Academy of Social Sciences.

"It's a relatively short time compared to overseas people in Hong Kong, who tend to stay for an average of 46 months," he told the Global Times yesterday. "Many overseas residents in Shanghai tend to return home when starting a family due to better education and medical care abroad."

That is, however, not to say that Shanghai's preferential policies for overseas talents have failed, according to the study, which said that 104,300 people, or 50.1 percent of the city's overseas population, have come to the city primarily for work. Employment has driven an even higher proportion of overseas adults from Hong Kong, Taiwan and Macao to Shanghai, with over 74 percent of them not here to play.

Another 19.8 percent of the overseas population in the city, or 41,200 people, meanwhile, have come to study, said the report.