The coolant mix and amount has absolutely nothing to do with what comes out the tailpipe.
Unless, of course, you've got a failed head gasket. Does the exhaust smell sweetish? Does the coolant level in the rad drop when the engine's running? Strange temperature gauge behaviour? Does your oil look like a chocolate milkshake? If the answer to these is "yes," you've likely got a failed head gasket.
Otherwise, it might simply be normal moisture content in the exhaust, or even rainwater that's blown in while the car was sitting. If you don't have symptoms of a blown head gasket, drive the car until it's well warmed up and then check for water and steam coming out the tailpipe.