Why it is difficult to include water vapor in a graph that shows the percentages of various goes in the atmosphere?

It is difficult to include water vapor in a graph showing the percentages of various gases in the atmosphere because water vapor is highly variable, fluctuating significantly with temperature, humidity, and geographical location. Unlike the more stable gases like nitrogen and oxygen, which make up a constant proportion of the atmosphere, water vapor can range from nearly 0% to about 4% by volume, making it challenging to represent accurately. Additionally, it is a gaseous phase of water that changes with weather conditions, complicating its consistent quantification.