condition mean min max ZT0-3 20.549999999999997 20.549999999999997 20.549999999999997 ZT4-7 20.8 20.8 20.8 ZT8-11 17.7 17.7 17.7 ZT12-15 8.3 8.3 8.3 ZT16-19 43.25 43.25 43.25 ZT20-23 19.7 19.7 19.7