I think it's more like 0.003%. Here's a chart showing just what "Greenhouse Gases" are as a portion of our atmosphere:
The largest GG that is totally ignored in all of these computational excesses is H2O that can give us feet of rain, snow, and ice -- all because of cold. We need it to stay warm!
I got my decimal wrong- thanks for clarifying- that makes it even more miniscule- although your chart is indicating 3.4%?