condition mean min max ZT0-3 5.923715 5.46812 6.37931 ZT4-7 3.5416049999999997 3.5416049999999997 3.5416049999999997 ZT8-11 3.4958650000000002 3.4958650000000002 3.4958650000000002 ZT12-15 0 0 0 ZT16-19 5.501495 5.501495 5.501495 ZT20-23 4.49234 4.49234 4.49234