condition mean min max ZT0-3 5.9363166666666665 3.768375 7.314625 ZT4-7 3.73407 3.73407 3.73407 ZT8-11 3.7578050000000003 3.7578050000000003 3.7578050000000003 ZT12-15 6.5840075 6.49109 6.676925 ZT16-19 7.371575 7.371575 7.371575 ZT20-23 8.75713 8.75713 8.75713