condition mean min max ZT0-3 6.97728 6.97728 6.97728 ZT4-7 6.067595 6.067595 6.067595 ZT8-11 5.909905 5.909905 5.909905 ZT12-15 6.380755 6.380755 6.380755 ZT16-19 6.787789999999999 6.787789999999999 6.787789999999999 ZT20-23 5.99087 5.99087 5.99087