78.08% nitrogen
20.95% oxygen
an average of 0.247% water vapour (very variable)
& approximately 1% of other gases
These other gases are the noble gases consisting of :-
Argon (0.93%)
Neon (less than 0.01%)
Helium (less than 0.01%)
Krypton (less than 0.01%)
Xenon (less than 0.01%)
Radon (less than 0.01%)
Regarding non-Nobel gases, there is also Carbon dioxide at 0.038%, and tiny traces of Hydrogen.
There are minute quantities of many other gases, such as methyl iodide, produced by bio- and geo-chemical reactions and used in bio-chemical reactions in living organisms, and whose importance to all life even in concentrations of less than one part per million million is only just beginning to be realised.