condition mean min max ZT0-3 8.446746 8.446746 8.446746 ZT4-7 8.757905000000001 8.757905000000001 8.757905000000001 ZT8-11 9.0494005 9.0494005 9.0494005 ZT12-15 8.184728 8.184728 8.184728 ZT16-19 7.8698145 7.8698145 7.8698145 ZT20-23 9.234891999999999 9.234891999999999 9.234891999999999