condition mean min max ZT0-3 15.6 15.6 15.6 ZT4-7 1.2 1.2 1.2 ZT8-11 8.700000000000001 8.700000000000001 8.700000000000001 ZT12-15 3.9000000000000004 3.9000000000000004 3.9000000000000004 ZT16-19 20.8 20.8 20.8 ZT20-23 17.75 17.75 17.75