condition mean min max ZT0-3 3.407895 2.94563 3.87016 ZT4-7 2.766395 2.766395 2.766395 ZT8-11 4.78509 4.78509 4.78509 ZT12-15 0 0 0 ZT16-19 8.809175 8.809175 8.809175 ZT20-23 6.60852 6.60852 6.60852