condition mean min max ZT0-3 4.550000000000001 4.550000000000001 4.550000000000001 ZT4-7 5.7 5.7 5.7 ZT8-11 7.3999999999999995 7.3999999999999995 7.3999999999999995 ZT12-15 6.05 6.05 6.05 ZT16-19 6.6 6.6 6.6 ZT20-23 7.35 7.35 7.35