condition mean min max ZT0-3 8.9 8.9 8.9 ZT4-7 6.5 6.5 6.5 ZT8-11 6.550000000000001 6.550000000000001 6.550000000000001 ZT12-15 18.45 18.45 18.45 ZT16-19 3.8 3.8 3.8 ZT20-23 18.4 18.4 18.4