condition mean min max ZT0-3 6.657988333333334 4.07547 9.981425000000002 ZT4-7 8.00811 8.00811 8.00811 ZT8-11 3.73714 3.73714 3.73714 ZT12-15 2.362005 1.96997 2.75404 ZT16-19 0.586677 0.586677 0.586677 ZT20-23 0.858384 0.858384 0.858384