condition mean min max ZT0-3 2.696588333333333 2.070595 3.02313 ZT4-7 2.816855 2.816855 2.816855 ZT8-11 3.1739100000000002 3.1739100000000002 3.1739100000000002 ZT12-15 8.766179999999999 8.429829999999999 9.10253 ZT16-19 7.978244999999999 7.978244999999999 7.978244999999999 ZT20-23 5.92405 5.92405 5.92405