Table 1 includes the detailed description of sample. Although the average age of residents in Beijing and Shanghai is slightly higher the than that of Xi’an and Chengdu, there are no significant differences in gender distribution across the cities. There is a slightly higher percentage of married couples in the first-tier cities than in the second-tier ones. In terms of occupational background, the percentage of professionals and service personnel is significantly higher in the first-tier cities than in the second-tier cities. In terms of income, the portion of higher categories in Beijing and Shanghai is significantly higher than that in the second-tier cities. The percentage of people reporting no regular income in Beijing and Shanghai is slightly perhaps reflecting the higher average age