The expanding ranks of the middle class in the capital has grown to 5.4 million, some 40 percent of the city's permanent residents, according to a report released on July 17.

The study, which was published by the Social Science Academic Press and Beijing University of Technology, said the average income of a member of the middle class in Beijing is about 5,923 yuan per month. The total income of the average Beijing middle class family is 10,007 yuan per month.

According to a report from the World Bank in 2006, the middle class in developing countries should be defined as those people with a per capita income of $ 4,000 (about 27,100 yuan) or more. The average annual income of a member of the middle class in Beijing is 71,076 yuan, which is about 43,976 yuan more than the bottom line.

The World Bank also reported that only six developing countries in 2006 had a middle class that comprised more than 40 percent of their total population. According to the report released on Saturday, the middle class nationwide only accounts for 23 percent.

However, some Beijingers who qualify as members of the middle class because of the size of their income said they did not think of themselves as middle class.

"I am far from being middle class, even though I can earn more than 6,000 yuan every month," said a man surnamed Zhu, who works at a State-owned enterprise in the capital.

Zhu said he rents a two-room apartment that he shares with a roommate and takes the subway to work everyday. He said his salary sounds good but it is still difficult to live in the city on what he earns.

"I think a middle class lifestyle should be more relaxed and at least people who are middle class should be able to buy what they need, including a house and vehicle," Zhu said.

The report said that income is not the only index by which to define middle class. Middle class people should earn their income from their intelligence and not by manual labor, and they should own middle-level economic and organizational resources.

According to the report, Zhu should be categorized as being in the lower level of the middle class, which occupies about 68.5 percent of the middle class. Their average income is only 2,947.76 yuan per month and most of them are junior office workers or self-employed laborers.

The top end of the middle class is made up of 675,000 Beijingers whose average monthly income is 9,666.67 yuan.

Statistics from the Beijing Statistic Information Bureau show that the average wage in Beijing across all classes in 2009 was 4,037 yuan per month, which is 1,886 yuan less than a middle class income.

Average wages in Beijing vary from industry to industry. Average wages in 10 industries were lower than the average social wage last year.

The poorest wages last year were in the resident service industry, which paid an average of 1,787.83 yuan per month.

The average wages paid in nine industries in the capital last year were higher than the average social wage, the best of all was in the financial industry, which paid workers an average of 14,515.25 yuan each month.