China's economic growth of the last 20 years has generally been met with declining happiness, especially among the poorest members of society, according to a US analysis published on Monday.

The study in the journal Proceedings of the National Academy of Sciences (PNAS) is based on six different surveys on self-reported satisfaction with life since 1990, a period when China's gross domestic product per capita increased fourfold.

"There are many who believe that well-being is increased by economic growth, and that the faster the growth, the happier people are. There could hardly be a better country than China to test these expectations," said lead author Richard Easterlin, professor of economics at the University of Southern California.

"But there is no evidence of a marked increase in life satisfaction in China of the magnitude that might have been expected due to the enormous multiplication in per capita consumption," said Easterlin, who is known for his work in the 1970s on how happiness is often not linked to wealth, coined the Easterlin Paradox.

"Indeed people are slightly less happy overall, and China has gone from being one of the most egalitarian countries in the world in terms of life satisfaction to one of the least."

In 1990, 68 percent of those in the wealthiest income bracket and 65 percent of those in the poorest reported high levels of satisfaction.

But the latter figure has fallen more than 23 percentage points in the past two decades, according to the USC analysis of surveys carried out by the Pew Research Center, Gallup, and Horizon Research Consultancy Group, among others.

Only 42 percent of Chinese people in the lowest income bracket reported high levels of life satisfaction in 2010, said the PNAS report.

Meanwhile, the wealthiest Chinese who said they were satisfied with their lives grew about three percentage points, to 71 percent.

"There is no evidence of a substantial uptrend in life satisfaction of the magnitude that might have been expected given the fourfold increase in GDP per capita over the study period," said the study.

While the surveys did not document the reasons for the decline, it is a well-known phenomenon that "growth in aspirations induced by rising income undercuts the increase in life satisfaction related to rising income itself," said the study.

Other reasons may include "home life and the need for a secure job to support it, health, friends and relatives," it added.

Similar trends have been observed in the former Soviet Union and East Germany during their transition periods.

But the study cautioned that it would be "a mistake to conclude from the life satisfaction experience of China, and the transition countries more generally, that a return to socialism and the gross inefficiencies of central planning would be beneficial."

Instead, leaders should take note that "jobs and job and income security, together with a social safety net, are of critical importance to life satisfaction."

The study also applauded the Chinese government for taking steps in the last few years to "repair the social safety net," which it described as "encouraging" for the country's least advantaged citizens.