To calculate percent of a total (i.e. calculate a percent distribution), you can use a formula that simply divides an amount by the total.
Note: you must format the result using the Percentage number format in Excel to see 25%, 10%, etc.
the reference to C11 is absolute (i.e. $C$11) so that it won't change when the formula is copied down the column.
As always in Excel, when you want to display a percentage, you need to use the Percentage number format, which will automatically display a decimal value as a percentage.
-dave bruns