condition mean min max ZT0-3 18.361347 18.361347 18.361347 ZT4-7 16.606379 16.606379 16.606379 ZT8-11 18.993868 18.993868 18.993868 ZT12-15 19.997583499999998 19.997583499999998 19.997583499999998 ZT16-19 20.2597795 20.2597795 20.2597795 ZT20-23 19.297553999999998 19.297553999999998 19.297553999999998