condition mean min max ZT0-3 7.597265 7.597265 7.597265 ZT4-7 6.61021 6.61021 6.61021 ZT8-11 6.19511 6.19511 6.19511 ZT12-15 6.430854999999999 6.430854999999999 6.430854999999999 ZT16-19 7.318115 7.318115 7.318115 ZT20-23 6.914925 6.914925 6.914925