condition mean min max ZT0-3 6.2 6.2 6.2 ZT4-7 25.6 25.6 25.6 ZT8-11 31.85 31.85 31.85 ZT12-15 6.85 6.85 6.85 ZT16-19 14.600000000000001 14.600000000000001 14.600000000000001 ZT20-23 29.2 29.2 29.2