Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere?

Explanation

In the environment the percentage of the gases like oxygen, nitrogen and carbon dioxide is minatined by their cyclic flow. The oxygen cycle, nitrogen cycle and carbon cycle respectively operate continuously in the nature by the constant interaction between the biotic and abiotic components of the biosphere. These interactions consist of a transfer of matter and energy between the different components of the biosphere. Thus, their levels in the atmosphere is maintained constantly up to required limit.