Pivot table: Adding a % to summarize categories

Perhaps using a calculated item:
1. For 'Grand Total': ='1' +'2' +'3' +'4' +'5'
2. For 'Top Two': =('4' +'5' )/'Grand Total'
Two issues
1. Each cell in H5:H8 has to be individually formatted using Format Cells as attempting to use Number Format changes the values in columns B:G to percentages as well
2. The Grand Total of the 'Top Two' column is a sum of the percentages in H5:H8 instead of a percentage of (E9+F9)/G9
Let us know if you have any questions.

Here is another possibility that employs Power Pivot.
1. Convert the data on the sample data sheet into an Excel table
2. Add the table to the data model
3. Produce the following measures
Count Rating:=COUNT(tbl_Data[Rating])
Count Top Two:=CALCULATE(COUNT(tbl_Data[Rating]),tbl_Data[Rating]>=4)
Top Two:=[Count Top Two]/[Count Rating]
4. Pull the Count Rating and Top Two fields into the Values area
5. Number Format the Top Two field as Percentage
Note that columns E, G, I, K and M are hidden as they display unnecessary (confusing) percentages.
Let us know if you have any questions.