condition mean min max ZT0-3 3.270665 2.87636 3.66497 ZT4-7 2.8557699999999997 2.8557699999999997 2.8557699999999997 ZT8-11 3.72422 3.72422 3.72422 ZT12-15 0 0 0 ZT16-19 3.730095 3.730095 3.730095 ZT20-23 3.805365 3.805365 3.805365