Community Property Calculation for 401k?

[401KSplit]

I am getting a divorce in CA. How do you calculate the portion of a 401K that is community property? I worked for a company from 1989 to 2002 and contributed to a 401K. I left the company in 2002 but the money stayed in the 401K account and has grown. I was married the fall of 2000 and contributed from 2000 to 2002. Is the community property calculated by the total amount of the account now minus the amount the account was worth on the date of marriage, or is community property only the amount contributed during the marriage plus the amount "that" amount went up? Please help! Thank you.