dynamic weighted average measure w/o creating additional tables

Below is a screenshot of my data. I'm attempting to calculate the weighted average percentage increase in employees for weeks up to the last week of data for TY Employees. I've used the following code to do this statically: % Change in Employees YTD = CALCULATE(SUM(Hours[TY Employees])/SUM(Hours[LY Employees])-1, FILTER(WeekBridge, WeekBridge[Week]<=8)). TY Employees and LY employees are both calculated columns. The code above was used to create the card with 16.9% to the right. 

Does anyone know how to do this dynamically without creating additional tables? Please advise if you need additional information to answer the question. Thanks in advance!