Kill game "bet size"

I played in the Mandalay Bay $4-$8 half-kill game on Friday (kill pots play as $6-$12). I'm looking to record my results but I can't figure out how many "big bets" to record, as mostly the BB is $8, but sometimes it's $12. I'm not sure how often kill pots come up in these games (this one was fairly loose).

Can anyone come up with a suggestion for how to estimate the average size of the BB?

[Xhad]

I made an attempt here (http://forumserver.twoplustwo.com/showthreaded.php?Cat=&Number=2924185&page=&view=&s b=5&o=&vc=1) , though the determining factor is frequency of kill pots.