Cumulative Total with duplicates

[joshcomputer1]

I need to create a calculated column like the yellow one below.  *This is a simplified view of the scenario. This cannot be a measure. What is does is it takes the Growth% for the month then adds it to the next month.  The formula I have now:

Cumulative = calculate(sum(Table1[Growth %]),

     Allexcept(Table1, Table1[Date]),

      Table1[Date]<= earlier(Table1[Date]))

This does a cumulative sum but it sums all of the Growth% column for that month.  I just want the first entry or an average.  If I swap sum with average then it doesn't do a cumulative total.  

[Greg_Deckler · Accepted solution]

You were pretty close, I think you want something like:

Cumulative = 
VAR __table = SUMMARIZE(FILTER(ALL(Table15),[Date]<=EARLIER([Date])),[Date],"__growth%",MAX([Growth %]))
RETURN
SUMX(__table,[__growth%])

See Table 15 of attached.