condition mean min max ZT0-3 4.230795 4.134535 4.327055 ZT4-7 4.45315 4.45315 4.45315 ZT8-11 2.70606 2.70606 2.70606 ZT12-15 0 0 0 ZT16-19 2.4108509999999996 2.4108509999999996 2.4108509999999996 ZT20-23 6.4985 6.4985 6.4985