condition mean min max ZT0-3 18.15 18.15 18.15 ZT4-7 13.7 13.7 13.7 ZT8-11 2.85 2.85 2.85 ZT12-15 2.5500000000000003 2.5500000000000003 2.5500000000000003 ZT16-19 20.5 20.5 20.5 ZT20-23 6.95 6.95 6.95