condition mean min max ZT0-3 3.448405 3.448405 3.448405 ZT4-7 2.69651 2.69651 2.69651 ZT8-11 3.75779 3.75779 3.75779 ZT12-15 4.16647 4.16647 4.16647 ZT16-19 4.570145 4.570145 4.570145 ZT20-23 5.234445 5.234445 5.234445