22% means 22 out of 100.
Each "hundredth", 2 places after a decimal point, is representative of one "part" of 100 total parts, those 100 parts being 1 whole.
Like 1.34 means 1 whole (100 whole parts) with an additional 30 parts (the tenths place) plus another 4 parts (hundredths place).
So, getting back to 22% as a decimal, 22% is twenty parts (two tenths) plus 2 parts (two hundredths).
You'd write it as .22