condition mean min max ZT0-3 7.765883333333333 6.199375 8.94507 ZT4-7 6.5714950000000005 6.5714950000000005 6.5714950000000005 ZT8-11 2.28299 2.28299 2.28299 ZT12-15 3.532275 2.332605 4.731945 ZT16-19 2.58018 2.58018 2.58018 ZT20-23 4.521255 4.521255 4.521255