Change the measure to show you % of total (click the dropdown, go to quick table calculations, & select % of total).
You may have to tweak the calculation based on what you're trying to depict
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If you wish to change the format of the number to a percentage, you would right click on the measure you wish to modify, choose Default Properties | Number Format. Once in Number Format, select Percentage followed by the number of digits beyond the decimal you wish to see (see screen capture below). Click OK and your numbers should now change to percentages.
If the number actually needs to be divided by 100 first, create a calculated field that does so, then change the number format of this field to Percentage.
Hope this helps,
Change to Percent.jpg 33.0 KB