condition mean min max ZT0-3 2.6 2.6 2.6 ZT4-7 3.8 3.8 3.8 ZT8-11 5.0 5.0 5.0 ZT12-15 4.6 4.6 4.6 ZT16-19 12.100000000000001 12.100000000000001 12.100000000000001 ZT20-23 4.8 4.8 4.8