set output 'co2_trend_a.ps' 
set term postscript color enhanced 'Helvetica,18'  
set grid 
set key top right 
set ylabel 'CO_2 concentration (parts per million) ' 
set xlabel 'Year ' 
set title 'Measurements from Mauna Kea, corrected for seasonal trends '
plot [][300:420] 'co2_mm_mlo.txt' using ($3):($6)      with points lt 1 lc 1 pt 3 ps 0.8 lw 3 t ''  
set output 
quit 
