condition mean min max ZT0-3 19.910376666666668 7.28868 26.52515 ZT4-7 6.81601 6.81601 6.81601 ZT8-11 8.78524 8.78524 8.78524 ZT12-15 11.6673175 8.757685 14.57695 ZT16-19 18.37095 18.37095 18.37095 ZT20-23 26.022 26.022 26.022