condition mean min max ZT0-3 16.449591 16.449591 16.449591 ZT4-7 19.5764635 19.5764635 19.5764635 ZT8-11 22.5520585 22.5520585 22.5520585 ZT12-15 25.2202755 25.2202755 25.2202755 ZT16-19 21.7032315 21.7032315 21.7032315 ZT20-23 17.0941735 17.0941735 17.0941735