condition mean min max ZT0-3 30.70685 30.70685 30.70685 ZT4-7 20.85065 20.85065 20.85065 ZT8-11 11.5378 11.5378 11.5378 ZT12-15 15.8417 15.8417 15.8417 ZT16-19 20.8342 20.8342 20.8342 ZT20-23 35.19815 35.19815 35.19815