condition mean min max ZT0-3 8.950000000000001 8.950000000000001 8.950000000000001 ZT4-7 2.0 2.0 2.0 ZT8-11 5.9 5.9 5.9 ZT12-15 20.1 20.1 20.1 ZT16-19 28.549999999999997 28.549999999999997 28.549999999999997 ZT20-23 23.75 23.75 23.75