condition mean min max ZT0-3 12.0678925 11.258485 12.8773 ZT4-7 7.06235 7.06235 7.06235 ZT8-11 8.23424 8.23424 8.23424 ZT12-15 0 0 0 ZT16-19 9.596815 9.596815 9.596815 ZT20-23 9.551839999999999 9.551839999999999 9.551839999999999