gas tank

I have just bought a 89 civic wagovan. I drove the car 1500 miles across america and then turned around and came back to South Carolina with it. I was suprised how well it did on fuel. I wanted to figure out just what the mileage was... but I have not been able to find the size of the gas tank. I read my chiltons and I did not see it in the maual.

Anyone know for sure the size of the tank?

thank you,

-Benevolance