condition mean min max ZT0-3 5.946515 5.946515 5.946515 ZT4-7 4.53862 4.53862 4.53862 ZT8-11 3.43828 3.43828 3.43828 ZT12-15 4.67333 4.67333 4.67333 ZT16-19 5.36023 5.36023 5.36023 ZT20-23 7.165315 7.165315 7.165315