condition mean min max ZT0-3 8.399012500000001 8.118455 8.67957 ZT4-7 9.515915 9.515915 9.515915 ZT8-11 7.07474 7.07474 7.07474 ZT12-15 0 0 0 ZT16-19 10.860510000000001 10.860510000000001 10.860510000000001 ZT20-23 12.04055 12.04055 12.04055