condition mean min max ZT0-3 17.544402 17.544402 17.544402 ZT4-7 18.9027995 18.9027995 18.9027995 ZT8-11 16.786365 16.786365 16.786365 ZT12-15 15.0335665 15.0335665 15.0335665 ZT16-19 23.3945065 23.3945065 23.3945065 ZT20-23 22.3842655 22.3842655 22.3842655