All you need to do is create a new Formula Column, and use the Col Cumulative Sum() function
- Create a new column
- Go to the header of the new column, and right click and select "Formula"
- In the formula, go to the left edge of the window to the List of function categories and click on "Statistical"
- From the displayed list, select "Col Cumulative Sum()"
- Now go to the list of columns and double click on the column you want to sum
- Finally click on "OK"
Jim