In the green frog, 49% of the oxygen enters through the lungs. How does 51% of oxygen get into her body?

The green frog, like other representatives of the class of amphibians (they are also called amphibians), has several respiratory organs. They can breathe with their lungs, but their lungs are not very developed and cannot swallow all the oxygen they need. And therefore, the skin of these animals is also involved in the exchange of gases. And when frogs just hatch from eggs and live only in water, they have gills, like fish. All this is explained by the fact that amphibians are an intermediate species between aquatic and terrestrial animals.