condition mean min max ZT0-3 5.203505 5.203505 5.203505 ZT4-7 2.92234 2.92234 2.92234 ZT8-11 2.1966099999999997 2.1966099999999997 2.1966099999999997 ZT12-15 4.328315 4.328315 4.328315 ZT16-19 5.01387 5.01387 5.01387 ZT20-23 6.95254 6.95254 6.95254