FWIW -- Atmospheric CO2 -- November, 2019, Data

Link here.

 

November, 2018, data here. It was 408.02.

410.27 / 1,000,000
- 408.02 / 1,000,000
= 2.25 / 1,000,000
= 0.00000225
= 0.000225%

My math is wrong, and has been questioned. See first comment. 

Posted the other day:

They say global warming could increase global temperatures by as much as three degrees. Okay. I'm kind of hoping for an increase of seven to ten degrees. Just saying.