condition mean min max ZT0-3 6.05901 5.64837 6.473265 ZT4-7 5.770365 5.770365 5.770365 ZT8-11 4.8134999999999994 4.8134999999999994 4.8134999999999994 ZT12-15 4.107825 1.7217149999999999 6.4939350000000005 ZT16-19 10.93349 10.93349 10.93349 ZT20-23 8.525985 8.525985 8.525985