condition mean min max ZT0-3 6.2221166666666665 3.309915 8.03587 ZT4-7 3.51576 3.51576 3.51576 ZT8-11 6.64082 6.64082 6.64082 ZT12-15 5.1838225 4.85935 5.508295 ZT16-19 4.49177 4.49177 4.49177 ZT20-23 6.22334 6.22334 6.22334