I have 2 years worth of data . I want to do an efficiency index with following formulae :

Highest impressions in Any Week in 2 years / Impressions this( selected ) week .

The Approach I thought could work was that I will need to calculate Impressions PER week for all Dates using Calculated Measure .

I have tried with

_SUMWeeklyImpressions = CALCULATE(

SUM(ImpressionShare[Impressions]),

ALLEXCEPT(‘Date’,‘Date’[FW Week Year])

)

However, ALL Except is not working .

Date table is linked with the other table .

I have attached file for reference here .

Data-Problem.pbix (1.1 MB)