condition mean min max ZT0-3 6.4507825 6.173985 6.72758 ZT4-7 8.2884 8.2884 8.2884 ZT8-11 8.970085000000001 8.970085000000001 8.970085000000001 ZT12-15 0 0 0 ZT16-19 1.6762299999999999 1.6762299999999999 1.6762299999999999 ZT20-23 3.9291150000000004 3.9291150000000004 3.9291150000000004