condition mean min max ZT0-3 1.4780983333333333 1.26504 1.759585 ZT4-7 1.85616 1.85616 1.85616 ZT8-11 2.3563650000000003 2.3563650000000003 2.3563650000000003 ZT12-15 7.090809999999999 6.50531 7.67631 ZT16-19 4.460710000000001 4.460710000000001 4.460710000000001 ZT20-23 5.081429999999999 5.081429999999999 5.081429999999999