condition mean min max ZT0-3 2.0166555 1.0537415 2.691745 ZT4-7 2.9418550000000003 2.9418550000000003 2.9418550000000003 ZT8-11 0.7919035000000001 0.7919035000000001 0.7919035000000001 ZT12-15 1.15725275 1.1166025 1.1979030000000002 ZT16-19 0.3831635 0.3831635 0.3831635 ZT20-23 0.771574 0.771574 0.771574