Thank you for your post.
It is better if you import the data into FileMaker Pro as raw data. You can always format the field in FileMaker Pro to display as a percentage. For example, if the value is .87 and you want it to display 87%, pull down the View menu and select "Layout Mode". Then, click on the Number field that you want to format, pull down the Format menu and select "Number". Select the option "Decimal", check the option for "Use notation", and select "Percent" from the pop-up. Adjust the number of decimal points (if desired) and click OK. The field will now display 87%.