Most, if not all, Chinese have become richer thanks to 28 years of reform and opening up. But are we any happier? Various surveys attempt to answer this question. Though experts have presented varying percentages based on different standards, their answers tend to find we are generally happier, and the number of optimists rises each year. The Chinese Academy of Social Sciences' 2006 Blue Book on social progress says 70 per cent of rural and urban citizens surveyed in 2005 reported a feeling of happiness and were optimistic about their futures. But each survey shows a worrisome fact that 10 per cent, at the lowest, of citizens were not content with their lives or not hopeful about the future. We cannot be content with the fact that at least 130 million of our countrymen are not happy. Although a sense of happiness remains a luxury for many of our countrymen because of poverty, we agree wealth is not the only factor of happiness. For most of us, except the extremely rich and naturally born optimists, there simply are too many variables   that may kill the feeling of happiness. These include, but are not limited to, rising housing prices, tight and instable job market, back-breaking schooling expenses and medical bills. The most common one, however, is a low sense of security  . Some experts pointed that in the low-and-middle income group there was too much uncertainty regarding employment, income, housing, medical situations, and education. How can you feel happy when you always have to prepare yourself for the unexpected? It may be beyond the government's reach, not to mention duty, to guarantee   higher income for every citizen. But it does have a burden to create an environment where all citizens can feel a reasonable level of security. The following factors of happiness are mentioned in the passage EXCEPT   _  .
security environment wealth employment