condition mean min max ZT0-3 3.509095 3.509095 3.509095 ZT4-7 4.23634 4.23634 4.23634 ZT8-11 6.036175 6.036175 6.036175 ZT12-15 4.3413 4.3413 4.3413 ZT16-19 2.607215 2.607215 2.607215 ZT20-23 2.916535 2.916535 2.916535