In particular, a gain in life expectancy at birth of slightly more than one year for both females and males over the period 1991-2003 could be attributed to the increase in health care spending per capita which amounted to more than 50% in real terms over the same period (Table 2). It also suggested that health care spending is the single most important factor explaining differences in health status across countries, though other factors also play important roles (Table 3). The implicit assumption is that all the unexplained country-specific effects and residuals reflect inefficiency, and not measurement errors, omitted variables and other factors. Supporting this assumption are the very low correlations, if any, between the unexplained differences in health status indicators and recent values of key variables which could not be included in panel regressions because cross-country comparable time series were not available - in particular income dispersion (as measured by Gini coefficient), obesity and population density.