condition mean min max ZT0-3 17.186896 17.186896 17.186896 ZT4-7 15.0336645 15.0336645 15.0336645 ZT8-11 12.9516485 12.9516485 12.9516485 ZT12-15 15.21567 15.21567 15.21567 ZT16-19 11.169422999999998 11.169422999999998 11.169422999999998 ZT20-23 12.541422 12.541422 12.541422