condition mean min max ZT0-3 4.982948333333333 4.275955 5.542105 ZT4-7 4.35811 4.35811 4.35811 ZT8-11 3.77979 3.77979 3.77979 ZT12-15 3.829915 3.4819649999999998 4.177865000000001 ZT16-19 3.50528 3.50528 3.50528 ZT20-23 5.222125 5.222125 5.222125