Calculating strike rate

I thought I'd take a look at X-Feeder for a change, and as per usual I'm struggling with the basics.

What I would like to do is follow the card derby, and keep a note of the strike rate of the suits. For example, I would like to be able to look at the last (say) 12 games, and work out the percentage of times each suit has won.

I'm guessing I would need to keep 12 user variables, and move the win markers along every game. But how do I know which suit has won? Would I have to do virtual bets, and keep a tally of wins? If I do that, how do I keep real bets separate from virtual ones? In order to do that, I also presume I'd have to keep four sessions running, one for each suit?

Am I asking the impossible, have I missed something simple, or does it just sound too horrible to contemplate? 

If you setup 4 user variables, one for each suit and set a trigger to do, for example:-
Set user variable     spades     selwins_12 /12 * 100     all card derby    Spades   once per game     exactly   1
with no conditions, then at the start of each game the four variables will contain the percentage of wins in the previous 12 games, obviously this will not be accurate for the first 11 games when starting a new run, but will work fine from then on.

selwins_NUMBER gives you the number of times the selection has won in the previous NUMBER of games.
/12 * 100 just converts to percentage.

That's great atjbet, thanks.
Not as difficult as I first suspected!