condition mean min max ZT0-3 6.293055 6.293055 6.293055 ZT4-7 3.76851 3.76851 3.76851 ZT8-11 2.718535 2.718535 2.718535 ZT12-15 4.80309 4.80309 4.80309 ZT16-19 6.554685 6.554685 6.554685 ZT20-23 5.69763 5.69763 5.69763