condition mean min max ZT0-3 9.647133 9.647133 9.647133 ZT4-7 8.6846955 8.6846955 8.6846955 ZT8-11 8.319085999999999 8.319085999999999 8.319085999999999 ZT12-15 8.6065155 8.6065155 8.6065155 ZT16-19 8.6059995 8.6059995 8.6059995 ZT20-23 8.481387 8.481387 8.481387