condition mean min max ZT0-3 6.8334925 6.530975 7.13601 ZT4-7 5.9487950000000005 5.9487950000000005 5.9487950000000005 ZT8-11 2.9902550000000003 2.9902550000000003 2.9902550000000003 ZT12-15 0 0 0 ZT16-19 4.89527 4.89527 4.89527 ZT20-23 6.7047349999999994 6.7047349999999994 6.7047349999999994