condition mean min max ZT0-3 7.38903 4.942959999999999 8.947585 ZT4-7 3.57325 3.57325 3.57325 ZT8-11 6.970219999999999 6.970219999999999 6.970219999999999 ZT12-15 4.65024 3.5080649999999998 5.792415 ZT16-19 6.504605 6.504605 6.504605 ZT20-23 7.763344999999999 7.763344999999999 7.763344999999999