condition mean min max ZT0-3 1.9 1.9 1.9 ZT4-7 1.5 1.5 1.5 ZT8-11 61.2 61.2 61.2 ZT12-15 3.8 3.8 3.8 ZT16-19 7.550000000000001 7.550000000000001 7.550000000000001 ZT20-23 12.2 12.2 12.2