Answer:
Nations with high income levels are most often developed or industrialized. Because these nations have wealthier economies, more citizens can afford access to healthcare. Nations with high income levels also enjoy high literacy rates, and therefore their population has more education to take preventative healthcare measures. High literacy rates also provide more qualified healthcare workers for the country. Nations with high income levels usually have stable governments with the resources to provide basic healthcare infrastructure, such as sanitation services and access to clean water. Finally, nations with high income levels typically also have lower birth rates. Therefore, they experience less population pressure on the existing infrastructure and healthcare system.