Forum:Special Event Drop Rates

I am curious if anyone has information on the drop rates for each level of the Special Event fighters. For example, with Alma, I have fought on the level 1 stage probably 30 times by now and haven't gotten a drop. I've also beat the level 2 stage about 5 times and haven't gotten her. I can't beat the third stage yet to test anything.

Is there any sort of set percentage of capturing these units? If so, what is it for each level? Having that info would be super awesome. :)