It's the total of everything I've done -- I just download from TDAmeritrade the spreadsheet of all SPY trades since 6/20.
If you're asking what the denominator was, it was total amount invested on the longs. I actually doubled up the position a few weeks in. For example, I had 20 long contracts to start and 3 weeks later had 40 -- so I counted the "cost" as the total 40.