condition mean min max ZT0-3 2.5670181666666667 1.2496695 4.9287 ZT4-7 3.61573 3.61573 3.61573 ZT8-11 0.8947229999999999 0.8947229999999999 0.8947229999999999 ZT12-15 2.6142025 2.39702 2.831385 ZT16-19 2.418735 2.418735 2.418735 ZT20-23 2.57217 2.57217 2.57217