If you want to display your pivot table values as a percentage of the total, there is a simple solution. You don’t need to create a new calculated field, you can just right-click the values, select Show Values As, % of Grand Total.

 

 

As well as showing the values as a % of Grand Total, there are a wealth of other options to choose from.

 

 

NB: If you want to display your results as values and percentages, you can drag the same field into the Values area twice and just re-format one of them as a % of Grand Total.