condition mean min max ZT0-3 5.592905 5.592905 5.592905 ZT4-7 5.680705 5.680705 5.680705 ZT8-11 7.015635 7.015635 7.015635 ZT12-15 6.6937549999999995 6.6937549999999995 6.6937549999999995 ZT16-19 9.022825000000001 9.022825000000001 9.022825000000001 ZT20-23 7.09827 7.09827 7.09827