condition mean min max ZT0-3 7.169695 7.05453 7.28486 ZT4-7 8.13904 8.13904 8.13904 ZT8-11 7.522715 7.522715 7.522715 ZT12-15 0 0 0 ZT16-19 7.3610050000000005 7.3610050000000005 7.3610050000000005 ZT20-23 7.996015 7.996015 7.996015