condition mean min max ZT0-3 18.8 18.8 18.8 ZT4-7 23.6 23.6 23.6 ZT8-11 9.6 9.6 9.6 ZT12-15 23.0 23.0 23.0 ZT16-19 6.8999999999999995 6.8999999999999995 6.8999999999999995 ZT20-23 21.1 21.1 21.1