Average growth in real taxable income in Australia, Canada and the United States, 1982-201015 Figure 4. Such comparisons have been used to argue that countries with higher levels of inequality of income are less healthy, less democratic and less happy and have more crime, more conflict and less intergenerational social mobility and equality of economic opportunity. However, these comparisons are primarily useful if we can depend on inequality' remaining stable and if we are interested in answering a question like: “what type of society would one like to live in?” Since this is an important question, and since there have been important periods in which levels of income inequality did not change much, most of the literature on income inequality has emphasized comparisons of the level of inequality.