condition mean min max ZT0-3 6.858067 6.858067 6.858067 ZT4-7 8.389258 8.389258 8.389258 ZT8-11 7.395218 7.395218 7.395218 ZT12-15 7.708523 7.708523 7.708523 ZT16-19 7.2778915 7.2778915 7.2778915 ZT20-23 7.7899674999999995 7.7899674999999995 7.7899674999999995