condition mean min max ZT0-3 3.1108616666666666 2.80333 3.703315 ZT4-7 1.8087399999999998 1.8087399999999998 1.8087399999999998 ZT8-11 2.6830800000000004 2.6830800000000004 2.6830800000000004 ZT12-15 5.7302975 4.916919999999999 6.543675 ZT16-19 6.519075 6.519075 6.519075 ZT20-23 5.360695 5.360695 5.360695