condition mean min max ZT0-3 8.809805 8.809805 8.809805 ZT4-7 7.236685 7.236685 7.236685 ZT8-11 5.93067 5.93067 5.93067 ZT12-15 6.145795 6.145795 6.145795 ZT16-19 8.12829 8.12829 8.12829 ZT20-23 8.759395 8.759395 8.759395