You should let people know about this. :-)
As you can imagine, the data is freely available. NASA has a page with some of the stats. Also, calculating the mass of the atmosphere is fairly straight forward. I used 4000 miles for the radius of the earth, and 15 #/sq in for the weight of the atmosphere. Both figures are close enough for proof-of-concept work. Several sites post the percentage of CO2 in the atmosphere both by volume (0.04%) and mass (0.06%). But people like to be stoned and stupid and subject to the thieving carnival barkers and shills and shellmen.