Is it true that the percentage of nitrogen in the atmosphere remains constant?

The percentage of nitrogen in the atmosphere remains relatively constant because of various natural processes such as lightning, nitrogen fixation, and the nitrogen cycle. 

Nitrogen fixation is the process by which certain bacteria convert atmospheric nitrogen into a form that can be used by living organisms. Lightning also plays a significant role in converting atmospheric nitrogen into a form that can be used by living organisms. The nitrogen cycle involves the movement of nitrogen between the atmosphere, soil, and living organisms, contributing to the constant percentage of nitrogen in the atmosphere.