All of the CO2 figures are annual averages.
Direct measurements of CO2 at Mauna Loa Observatory, in Hawaii began in March, 1958. This is the annual average data we've graphed:
For monthly data see:
1850-1958 data is from http://data.giss.nasa.gov/modelforce/ghgases/Fig1A.ext.txt (ice cores).
1800-1850 CO2 data is from http://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/law/law_co2.txt (Law Dome ice cores, 75 year smoothed).