According to this thesis, development policy could focus entirely on promoting economic growth, since such growth would ultimately lead to a decrease in inequality. In a comparative study of 98 countries, Barro (2000) shows that the Kuznets curve exhibits a certain degree of empirical regularity over time, but that it does relatively little to explain the variation in inequality across countries. As summarized by Castelar (2007), empirical studies, especially those conducted since 1996, show that high initial levels of inequality curb subsequent economic growth. Most of the literature on the subject indicates that a one standard deviation decrease in inequality boosts the annual per capita GDP growth rate by between 0.5 and 0.8 percentage points. However, when using panel data, the relationship between income inequality and economic growth appears to be weaker, which suggests that the empirical regularity seen in the Kuznets curve is robust for cross-sectional data but disappears when fixed country effects are introduced. Examples of these studies include those of Fields and Jakubson (1994), Fishlow (1972), Deineger and Squire (1998) and Barreto, Melo Neto and Tebaldi (2001).