condition mean min max ZT0-3 5.73653 5.73653 5.73653 ZT4-7 5.283415 5.283415 5.283415 ZT8-11 6.0169 6.0169 6.0169 ZT12-15 7.64391 7.64391 7.64391 ZT16-19 7.922065 7.922065 7.922065 ZT20-23 6.17736 6.17736 6.17736