condition mean min max ZT0-3 15.919925 15.750049999999998 16.0898 ZT4-7 15.03275 15.03275 15.03275 ZT8-11 17.958399999999997 17.958399999999997 17.958399999999997 ZT12-15 0 0 0 ZT16-19 26.0723 26.0723 26.0723 ZT20-23 15.33335 15.33335 15.33335