condition mean min max ZT0-3 8.8 8.8 8.8 ZT4-7 1.3 1.3 1.3 ZT8-11 4.8 4.8 4.8 ZT12-15 3.1500000000000004 3.1500000000000004 3.1500000000000004 ZT16-19 3.7 3.7 3.7 ZT20-23 19.349999999999998 19.349999999999998 19.349999999999998