This is an image of the graph I drew showing the development of countries based on their average life expectancy and GDP. The data used for this graph was collected in 2015, and it clearly shows that the greatest gap between the countries is in GDP. We can see that the southern countries, with exception of Singapore and Austrailia, are quite far from the northern countries in the sense of GDP. This is explained by the fact that these northern/western countries have a higher GDP, meaning they have more funds to spend on making healthcare better and more accessible, meaning they have a higher life expectancy.
There is one outlier. Congo is on the poorer side of the graph, but still much further down than most of the relatively poor countries. Congo is an outlier because there is no steady decline to its position. The other countries are in two clear groups – wealthy and poor – but there is a massive gap between the poor and congo.
