condition mean min max ZT0-3 6.9 6.9 6.9 ZT4-7 1.6 1.6 1.6 ZT8-11 0.75 0.75 0.75 ZT12-15 2.55 2.55 2.55 ZT16-19 12.049999999999999 12.049999999999999 12.049999999999999 ZT20-23 3.1500000000000004 3.1500000000000004 3.1500000000000004