Access Report - Percent of totals Calculation

[JenWest]

My report looks like this....

January 2004 Ads by Total Ads 5
AB 1
Domestic 1
World Select 1
CDC 2
Craft/Local 1
Breckenridge 1
Import 1
Corona 1
Western Beverage 2
Domestic Premium 1
Lite 1
Sub Premium 1
MHL 1

The total number of ads is 5. (MHL/Lite/Corona/Breckenridge/World Select) I need a formula to calcluate, of those 5 ads, what percent belongs to Western Beverage, or AB, or Coors, etc. So for Western it would be 2/5, but the 2 is the count of the 2 brands listed under Western Beverage (lite/MHL). My query looks like this.....

House Type of Brand Brand Name Brand CountOfBrand Name Date
AB Domestic Specialties World Select 19 1 01/22/04
CDC Craft/Local Breckenridge 25 1 01/15/04
CDC Import Corona 46 1 01/22/04
Western Beverage Domestic Premium Lite 64 1 01/15/04
Western Beverage Sub Premium MHL 1 1 01/31/04

can you help???