condition mean min max ZT0-3 9.472281 9.472281 9.472281 ZT4-7 8.6096515 8.6096515 8.6096515 ZT8-11 8.0268355 8.0268355 8.0268355 ZT12-15 8.281712 8.281712 8.281712 ZT16-19 8.8804725 8.8804725 8.8804725 ZT20-23 7.9053130000000005 7.9053130000000005 7.9053130000000005