How to sum a range in each cell?

I have a list of table as below - "Year" and "Sales". How do I calculate a new variable to have 15-year cumulative sales for year of 2016 equal to sum of sales between 2002 to 2016 (= 646032),

sales for year of 2017 equal to sum of sales between 2003 to 2017 (= 600154), etc.