condition mean min max ZT0-3 3485.198931 3485.198931 3485.198931 ZT4-7 3088.1890615 3088.1890615 3088.1890615 ZT8-11 2840.6339865 2840.6339865 2840.6339865 ZT12-15 3440.718024 3440.718024 3440.718024 ZT16-19 3500.6565505 3500.6565505 3500.6565505 ZT20-23 3196.5269485 3196.5269485 3196.5269485