Question $9$

Create a column that estimates the number of citable documents per person. What is the correlation between the number of citable documents per capita and the energy supply per capita? Use the $.$corr$()$ method, $($Pearson$\text{'}$s correlation$).$

This function should return a single number.

$($Optional: Use the built$-$in function plot$9()$ to visualize the relationship between Energy Supply per Capita vs$.$ Citable docs per Capita$)$