set terminal png size 1024,768
set key above horizontal autotitle columnheader
set bars 5.0
set style fill solid border -1
set xlabel "Date"
set ylabel "Hours"
set grid y
set xrange [*:1]
set xtics rotate by -45
plot "tasktime.dat" using 1:3:6:7:4:xtic(2) title 'Man Time Interval' \
    with candlesticks whiskerbars 0.5 lc rgb "#ee5555", \
     "tasktime.dat" using 1:8 title 'Overlap Mean' with lines lc rgb "green", \
     "tasktime.dat" using 1:5 title 'Man-Hour Mean' with lines lc rgb "black"