Shanghai's population grew 6.28 million in a decade to 23 million last year, with residents getting younger, better educated and nearly 40 percent coming from elsewhere, according the city census results released on Tuesday.

Of the 6.28 million, a 37.5 percent increase, 88 percent were migrants contributing to a total of nearly 9 million and 159.1 percent more than in 2000, the Shanghai Statistics Bureau reported.

The statistics recorded those who had lived in the municipality longer than six months.

"The number of migrants grew much faster than we expected, reflecting the rapid social and economic development of the city," said Yu Xuming, deputy director of Shanghai census office, on Tuesday.

The ratio of residents aged between 14 and 64 was 81.3 percent, 5 percent more than a decade ago.

More young workers coming to Shanghai has eased the city's notorious aging issue: Shanghai residents 65 or older account for 10.1 percent of the population, whereas the national average is 8.9 percent.

"Handling growing numbers of elderly parents who come with those young migrants has become the biggest challenge for us," said Gao Julan, deputy director of Shanghai Civil Affairs Bureau.

The ratio of people with degrees in Shanghai also increased from 11 to 22 percent, reflecting the influx.

"Simple administrative orders could never control the city's inflated population as it is driven by demand and development," said Zhou Haiwang, deputy director of Population Research Institute at the Shanghai Academy of Social Sciences.

The migrant surge has also increased the population of seven suburban districts by more than 50 percent, Yu said.