A baby boom has helped to push the population past seven million, according to figures released yesterday. The data, released by the Census and Statistics Department, shows 7,008,300 people were living in the city by the middle of the year, an increase of 0.4 per cent from the middle of last year - or 30,600 more people. An inflow of migrants from the mainland was another big factor behind the increase. Figures released earlier this year said the population had passed seven million by the end of last year. But the revised figures yesterday put the population at the end of last year at 6,988,900, or a 0.5 per cent year-on-year increase. The figures were extrapolated from the 2006 By-census by adding and subtracting births and deaths. Between the middle of last year and the middle of this year, 81,200 babies were born. New births, born to residents and non-residents, exceeded the overall population increase by 266 per cent. There were 39,900 deaths during the period. The inflow of one-way permit holders during the period was 41,400. Incoming one-way permit holders exceeded the overall population increase by 136 per cent. One-way permits are issued by the central government to eligible mainlanders who want to settle in Hong Kong to be reunited with their families. There is a daily quota of 150 such permits. In an interview with the Financial Times in 2007, Chief Executive Donald Tsang Yam-kuen said he thought Hong Kong's optimal size would be about 10 million.