condition mean min max ZT0-3 7.194585 7.194585 7.194585 ZT4-7 3.371665 3.371665 3.371665 ZT8-11 2.28715 2.28715 2.28715 ZT12-15 1.946085 1.946085 1.946085 ZT16-19 9.208 9.208 9.208 ZT20-23 4.923765 4.923765 4.923765