condition mean min max ZT0-3 8.461084 8.461084 8.461084 ZT4-7 8.220472000000001 8.220472000000001 8.220472000000001 ZT8-11 7.8895525 7.8895525 7.8895525 ZT12-15 9.151448 9.151448 9.151448 ZT16-19 8.992762500000001 8.992762500000001 8.992762500000001 ZT20-23 8.868568 8.868568 8.868568