condition mean min max ZT0-3 6.050000000000001 6.050000000000001 6.050000000000001 ZT4-7 2.9 2.9 2.9 ZT8-11 7.4 7.4 7.4 ZT12-15 2.4000000000000004 2.4000000000000004 2.4000000000000004 ZT16-19 1.9 1.9 1.9 ZT20-23 4.55 4.55 4.55