grep discharging /var/lib/upower/history-rate-7.dat | sort -k2 | awk '{ a[i++]=$2; } END { print a[int(i/2)]; }'
awk '{ if ($3 =="discharging") sum += $2 } END { if (NR > 0) print sum / NR }' < /var/lib/upower/history-rate-7.dat
grep discharging /var/lib/upower/history-rate-7.dat | sort -k2 | head