Sorry i misphrased that. They do not split equally it is based on a percentage basis, based on the number of flights into a destination. So taking NYC for example your ticket on AA the vast majority of that revenue would go to BA as they have the most flights 12 versus 4. Although AA would get a smaller share of the other 8 flights.
There were some actual numbers out there when they were applying for anti trust immunity with the joint venture. I will try and post a link tomorrow….