I guess number of searches done in google will be over 50% but.... it's not the number of search,, it's number of visits..right??? Yahoo has Yahoo stores and many things and so as msn... I think that's why google is so lower and msn and yahoo are higher.., than I think...
I always thought somehow that google is responsible for over 80% of all searches, but I don't remember where I read it..
People mostly go to yahoo because it has everything, it's the biggest portal, the same for MSN and google is mostly known by it's search function..