condition mean min max ZT0-3 2.2 2.2 2.2 ZT4-7 1.9 1.9 1.9 ZT8-11 5.25 5.25 5.25 ZT12-15 2.1 2.1 2.1 ZT16-19 10.049999999999999 10.049999999999999 10.049999999999999 ZT20-23 3.5 3.5 3.5