Report Page Tooltip - help with measures

Hello all,

I have a table full of people date, and one column is generation group (e.g. Baby Boomers, etc).  I then have a small table defining the generation groups and have a relationship between it and the main dataset. 

I have a donut chart which shows the count & percentage of  people by generation.  There's a mapping table for generation that I am using, so on the the donut chart, I am actually using the column from the mapping table.  The mapping file has a relationship between it and the main dataset (called HEADCOUNT).

I am really liking the new report page tooltips, so I built one.  To maintain the previous functionality, I included a measure for count.  The other measure that needs to be included to maintain functionality is percentage.  The problem is that i can't craft a measure that shows percentage in all cirumstances.

For example, neither of these work and will always display 100%,

Tooltip Percent = HEADCOUNT[count]/CALCULATE(HEADCOUNT[count],all(HEADCOUNT[Generation]))

Tooltip Percent = HEADCOUNT[count]/CALCULATE(HEADCOUNT[count],all('Mapping - Generation'[Generation]))

I have another donut chart for Gender, but I don't use a mapping file or a relationship.  The Legend is just the Gender column from the HEADCOUNT dataset.

This measure works fine:

Tooltip Percent = HEADCOUNT[count]/CALCULATE(HEADCOUNT[count],all(HEADCOUNT[Gender]))

I've had this problem before, where I simply cannot get calculate to behave as I want it to because of relationships.  In the above example, I want the denominator to count everyone and ignore any filters applied to Generation.  But the filter is actually applied to a column in a related table, and it is not ignored and I get 100% every time.