condition mean min max ZT0-3 2.422623166666667 1.1865795000000001 3.21959 ZT4-7 1.1557 1.1557 1.1557 ZT8-11 1.584355 1.584355 1.584355 ZT12-15 3.8021200000000004 3.4839650000000004 4.120275 ZT16-19 4.600815 4.600815 4.600815 ZT20-23 4.679425 4.679425 4.679425