condition mean min max ZT0-3 4.159173333333333 2.463785 5.465450000000001 ZT4-7 1.74093 1.74093 1.74093 ZT8-11 3.6163600000000002 3.6163600000000002 3.6163600000000002 ZT12-15 5.643765 5.118785 6.1687449999999995 ZT16-19 5.424405 5.424405 5.424405 ZT20-23 7.855885 7.855885 7.855885