How much money in Open Source for 2004?

Only in US, Over $200 million dollars if you count the 'big ones' (MySQL, Red Hat, JBoss, etc) That's a lot of money, and only the tip of the iceberg.

Money is flowing into open source startups at a furious pace, which makes me prompt the question:

Why aren't you starting one? (I am...)

I will dedicate myself to research how much money is invested in Mexico for these matters. But I can foresee it will be a daunting task since information in Mexico does not flow as easily as in US.
Does anyone have a good source for this?