condition mean min max ZT0-3 7.85 7.85 7.85 ZT4-7 18.6 18.6 18.6 ZT8-11 11.6 11.6 11.6 ZT12-15 2.05 2.05 2.05 ZT16-19 7.550000000000001 7.550000000000001 7.550000000000001 ZT20-23 23.3 23.3 23.3