condition mean min max ZT0-3 8.228795 5.282695 9.790455 ZT4-7 3.30766 3.30766 3.30766 ZT8-11 2.9009650000000002 2.9009650000000002 2.9009650000000002 ZT12-15 4.1834275000000005 3.619965 4.7468900000000005 ZT16-19 4.573525 4.573525 4.573525 ZT20-23 9.460655 9.460655 9.460655