condition mean min max ZT0-3 7.241921666666666 5.9907 7.868125 ZT4-7 8.524740000000001 8.524740000000001 8.524740000000001 ZT8-11 7.1473450000000005 7.1473450000000005 7.1473450000000005 ZT12-15 8.17737 5.69269 10.66205 ZT16-19 9.969715 9.969715 9.969715 ZT20-23 11.80775 11.80775 11.80775