condition mean min max ZT0-3 6.803593333333334 6.803593333333334 6.803593333333334 ZT4-7 3.03464 3.03464 3.03464 ZT8-11 2.369625 2.369625 2.369625 ZT12-15 3.8400600000000003 3.8400600000000003 3.8400600000000003 ZT16-19 3.13049 3.13049 3.13049 ZT20-23 4.98355 4.98355 4.98355