condition mean min max ZT0-3 4.723585 3.689755 5.333275 ZT4-7 4.022715 4.022715 4.022715 ZT8-11 4.942855 4.942855 4.942855 ZT12-15 6.182175 5.81745 6.5469 ZT16-19 5.52862 5.52862 5.52862 ZT20-23 6.74669 6.74669 6.74669