condition mean min max ZT0-3 9.013221 9.013221 9.013221 ZT4-7 7.951919 7.951919 7.951919 ZT8-11 8.243758 8.243758 8.243758 ZT12-15 8.175699 8.175699 8.175699 ZT16-19 8.6458735 8.6458735 8.6458735 ZT20-23 8.657895499999999 8.657895499999999 8.657895499999999