Access to health care is heavily influenced by socioeconomic status as well, as wealthier population groups have a higher probability of obtaining care when they need it. A study by Makinen et al. (2000) found that in the majority of developing countries they looked at, there was an upward trend by quintile in health care use for those reporting illness. Wealthier groups are also more likely to be seen by doctors and to receive medicine. There has been considerable research in recent years regarding a phenomenon known as food deserts, in which low access to fresh, healthy food in a neighborhood leads to poor consumer choices and options regarding diet. It is widely thought that food deserts are significant contributors to the childhood obesity epidemic in the United States and many other countries. This may have significant impacts on the local level as well as in broader contexts, such as in Greece, where the childhood obesity rate has skyrocketed in recent years heavily as a result of the rampant poverty and the resultant lack of access to fresh foods. The economies of the world have developed unevenly, historically, such that entire geographical regions were left mired in poverty and disease while others began to reduce poverty and disease on a wholesale basis. This was represented by a type of North–South divide that existed after World War II between First world, more developed, industrialized, wealthy countries and Third world countries, primarily as measured by GDP. From around 1980, however, through at least 2011, the GDP gap, while still wide, appeared to be closing and, in some more rapidly developing countries, life expectancies began to rise. However, there are numerous limitations of GDP as an economic indicator of social "well-being." If we look at the Gini coefficient for world income, over time, after World War II the global Gini coefficient sat at just under .45. From around 1959 to 1966, the global Gini increased sharply, to a peak of around .48 in 1966. After falling and leveling off a couple of times during a period from around 1967 to 1984, the Gini began to climb again in the mid-eighties until reaching a high or around .54 in 2000 then jumped again to around .70 in 2002. Since the late 1980s, the gap between some regions has markedly narrowed— between Asia and the advanced economies of the West, for example—but huge gaps remain globally. Overall equality across humanity, considered as individuals, has improved very little. Within the decade between 2003 and 2013, income inequality grew even in traditionally egalitarian countries like Germany, Sweden and Denmark. With a few exceptions—France, Japan, Spain—the top 10 percent of earners in most advanced economies raced ahead, while the bottom 10 percent fell further behind.