condition mean min max ZT0-3 9.399999999999999 9.399999999999999 9.399999999999999 ZT4-7 8.0 8.0 8.0 ZT8-11 6.75 6.75 6.75 ZT12-15 2.8 2.8 2.8 ZT16-19 8.05 8.05 8.05 ZT20-23 6.45 6.45 6.45