To see precise values, hover your mouse cursor over the red graph trace. (However, the ice core values are less accurate than the Mauna Loa measurements.)
Direct measurements of CO2 at Mauna Loa Observatory, in Hawaii began in March, 1958. That's the data we've used since then:
ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_annmean_mlo.txt (1959–2016), and
ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_mm_mlo.txt (July, 2017).
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).