condition mean min max ZT0-3 9.6 9.6 9.6 ZT4-7 1.8 1.8 1.8 ZT8-11 9.35 9.35 9.35 ZT12-15 12.100000000000001 12.100000000000001 12.100000000000001 ZT16-19 8.45 8.45 8.45 ZT20-23 18.15 18.15 18.15