condition mean min max ZT0-3 8.446746 8.446746 8.446746 ZT4-7 8.338295 8.338295 8.338295 ZT8-11 7.9809505 7.9809505 7.9809505 ZT12-15 9.1308565 9.1308565 9.1308565 ZT16-19 8.885456 8.885456 8.885456 ZT20-23 9.4456445 9.4456445 9.4456445