Column % change when selecting a filter

[prosell8]

Scenario:  Column created to calculates sales % based on a specific group of products.

Filter created to HIDE or SHOW products. 

When products are HIDDEN the % calculates correctly but when filter has SHOW products the % goes to 100 as its 1/1. 

I would like for the column to always stay at the correct value even when drilling down to product level. 

FORMULA:

sum(if([Product Family Name] <> 'CARS' ,([Sales QTY)))/Sum([Sales QTY])

FILTER:

SHOW = 100% (stays static)

HIDE = 2% ( obviously this number is not static)

Is there a way to avoid the column to change values as you drill down? 

[Gabbar]

Try this:-

Sum({<Product_family_name-={'Cars'}>}sales_quantity)/Sum({1}sales_quantity)

[Aasir]

sum(if([Product Family Name] <> 'CARS', [Sales QTY])) / Sum(TOTAL <[Product Family Name]> [Sales QTY])