condition mean min max ZT0-3 16.75 16.75 16.75 ZT4-7 6.5 6.5 6.5 ZT8-11 8.15 8.15 8.15 ZT12-15 10.399999999999999 10.399999999999999 10.399999999999999 ZT16-19 6.7 6.7 6.7 ZT20-23 6.45 6.45 6.45