condition mean min max ZT0-3 8.052595 8.052595 8.052595 ZT4-7 7.610785 7.610785 7.610785 ZT8-11 5.853965 5.853965 5.853965 ZT12-15 6.63366 6.63366 6.63366 ZT16-19 8.419855 8.419855 8.419855 ZT20-23 7.3243 7.3243 7.3243