condition mean min max ZT0-3 5.715785 5.715785 5.715785 ZT4-7 4.59629 4.59629 4.59629 ZT8-11 7.000565 7.000565 7.000565 ZT12-15 6.1321650000000005 6.1321650000000005 6.1321650000000005 ZT16-19 8.13818 8.13818 8.13818 ZT20-23 6.356535 6.356535 6.356535