condition mean min max ZT0-3 3.1999999999999997 3.1999999999999997 3.1999999999999997 ZT4-7 3.3 3.3 3.3 ZT8-11 4.2 4.2 4.2 ZT12-15 3.5500000000000003 3.5500000000000003 3.5500000000000003 ZT16-19 4.15 4.15 4.15 ZT20-23 2.75 2.75 2.75