Calculations with multiple dates

Hi everyone, 

I am working on an HR measure where we are trying to see how often leaders (positions) are changing in our organization. 

I have for each position, the employee who held the position, and the assignment start and end date. 

What I am trying to achieve is to count how many employees held a position in a year and assign a status (2 or less, perfect, 3 ok, more than 3 bad) and then calculate the % per department per year of how many positions are in each status. like this: 

Here is the link to the sample data: https://drive.google.com/file/d/1tOY_X2VUg6RMpSPljmdebQU8L4Vl8UC0/view?usp=sharing 

I can get the count to work by year by creating a date table with two inactive relationships, but to assign a status I created a sub-table from my main one, but  the date or year filter don't work on that table since the relationship is in active. 

Any help on this is appreciated. I might be going at it all wrong 😅since it's my first time working with data with multiple dates. 

Thanks