Last four quarters rate

If I understand you correctly you want to put all the Dates in to a YYYYQ format:

(YQ = Concatenate(DateField.[Year], Concatenate("Q", DateField[QuarterNo])) As a Column

Then you want a Total of the last 4 Quarters 

(L4QrAll = Calculate(Sum(ValueColumn), Filter(All(TableName), YQ  = // This is where I cannot make it dynamic however it will work but you will have to change it when we enter a new quater// "2019Q2" || YQ = "2019Q1" || YQ= "2018Q4" || YQ= "2018Q3")) As a Measure

Then a Measure for the Group Values

(L4QrEach = Calculate(Sum(ValueColumn), Filter(TableName, YQ  = "2019Q2" || YQ = "2019Q1" || YQ= "2018Q4" || YQ= "2018Q3")) As a Measure

Finally the Rate

Rate = Divide(L4QrEach, L4QrAll) As a Measure

Note:  This will not create a table like the one you had. This is due to level of detail. However, if you create a table like yours without the YQ field it will aggregate to the group level.

I hope this helps

This is the data I created to test it.