Calculate prevalence by disease in unpivoted table

[SophRow]

Hi experts,

I have a large dataset that looks (simplified!) like this:

For diseases, 0 = no disease and 1 = disease.

What I want to show is prevalence by cohort i.e., incidence / Total # participants in particular cohort. 

I also want to keep the Participant Number so I can later slice by gender age etc from a dimension table. 

I have played around with unpivoting the Disease columns and can calculate total incidence, but am not able to get prevalence to work on a visual (it always comes out at 100%). 

My DAX was simply:

Total Incidence = COUNTROWS('Table')

Total Distinct Participants = DISTINCTCOUNT('Table'[Participant Number])

Prevalence = DIVIDE([Total Incidence],[Total Distinct Participants])

Whilst this work in card visuals and can be filtered by cohort, it doesn't work on a bar chart to show by condition:

(Condition is the name of the unpivoted column).

Any advice greatly appreciated.

Best,

Soph