Created a column for the average and looking to put that into a map for each country based on average GDP.

How am I able to get the average GDP where the data is ranging from 1960-2018 and do this for each country. I can easily get the average for the first country but there are 212 countries in the dataset so don’t want to do it manually.
dataset

Many thanks.

I’ve tried using formulas but not sure how to do it for each country where it ranges from 1960-2018