condition mean min max ZT0-3 1.363626 1.363626 1.363626 ZT4-7 0.4822635 0.4822635 0.4822635 ZT8-11 0.7638265000000001 0.7638265000000001 0.7638265000000001 ZT12-15 0.42666 0.42666 0.42666 ZT16-19 1.2520756666666668 1.2520756666666668 1.2520756666666668 ZT20-23 1.757541 1.757541 1.757541