condition mean min max ZT0-3 4.5 4.5 4.5 ZT4-7 2.3 2.3 2.3 ZT8-11 6.800000000000001 6.800000000000001 6.800000000000001 ZT12-15 2.75 2.75 2.75 ZT16-19 3.5999999999999996 3.5999999999999996 3.5999999999999996 ZT20-23 8.4 8.4 8.4