condition mean min max ZT0-3 7.163871 7.163871 7.163871 ZT4-7 8.5025515 8.5025515 8.5025515 ZT8-11 9.484135 9.484135 9.484135 ZT12-15 9.070802 9.070802 9.070802 ZT16-19 8.6051585 8.6051585 8.6051585 ZT20-23 7.8260415 7.8260415 7.8260415