condition mean min max ZT0-3 4.037655 4.037655 4.037655 ZT4-7 5.728325 5.728325 5.728325 ZT8-11 4.669805 4.669805 4.669805 ZT12-15 3.47642 3.47642 3.47642 ZT16-19 3.879925 3.879925 3.879925 ZT20-23 5.876785 5.876785 5.876785