The small population density together with abundant natural resources and foreign private investment have helped make Gabon one of the most prosperous countries in the region, with the highest Human Development Index ranking (103rd of 182) in Sub-Saharan Africa. Its health care is also considered to be one of the best in West Africa, although there are still significant shortcomings. The main problem is the lack of quality health care outside Libreville, its capital. The government has sought to fix this by both more construction of mobile health units and a government subsidized insurance programme. It has also sought to create an open investment environment, by reducing pharmaceutical tariffs to zero.