condition mean min max ZT0-3 19.138225 18.46315 19.813299999999998 ZT4-7 22.29905 22.29905 22.29905 ZT8-11 16.260550000000002 16.260550000000002 16.260550000000002 ZT12-15 0 0 0 ZT16-19 17.5411 17.5411 17.5411 ZT20-23 18.03725 18.03725 18.03725