condition mean min max ZT0-3 6.300000000000001 6.300000000000001 6.300000000000001 ZT4-7 9.6 9.6 9.6 ZT8-11 23.6 23.6 23.6 ZT12-15 7.85 7.85 7.85 ZT16-19 8.75 8.75 8.75 ZT20-23 8.35 8.35 8.35