condition mean min max ZT0-3 9.552132 9.552132 9.552132 ZT4-7 8.564511 8.564511 8.564511 ZT8-11 8.526599000000001 8.526599000000001 8.526599000000001 ZT12-15 7.5715 7.5715 7.5715 ZT16-19 8.448616000000001 8.448616000000001 8.448616000000001 ZT20-23 8.026017 8.026017 8.026017