condition mean min max ZT0-3 16.123825 13.4483 18.79935 ZT4-7 17.8535 17.8535 17.8535 ZT8-11 21.71405 21.71405 21.71405 ZT12-15 0 0 0 ZT16-19 27.110300000000002 27.110300000000002 27.110300000000002 ZT20-23 17.75965 17.75965 17.75965