How much is the boiling point of coolant per one pound of pressure?

From the following website. http://www.evanscooling.com/articles/aug98oc.htm Modern cars, like many of those built after 1955, started using pressurized cooling systems. The benefit was that, for every pound of pressure created in the cooling system, the boiling point of the water was raised by three degrees. By sealing up the cooling system, and adding pressure, the boiling point of the water was raised. Then, the engine could be operated at a higher temperature and operated more efficiently. Today, most modern cars use a 16-lb. cap to raise the boiling point 48 degrees higher than the normal 212 degree boiling point.