condition mean min max ZT0-3 4.181755 4.181755 4.181755 ZT4-7 3.329365 3.329365 3.329365 ZT8-11 2.919925 2.919925 2.919925 ZT12-15 3.664545 3.664545 3.664545 ZT16-19 4.716105 4.716105 4.716105 ZT20-23 4.80645 4.80645 4.80645