condition mean min max ZT0-3 2.31492 2.31492 2.31492 ZT4-7 1.88799 1.88799 1.88799 ZT8-11 4.03045 4.03045 4.03045 ZT12-15 3.2187650000000003 3.2187650000000003 3.2187650000000003 ZT16-19 2.99621 2.99621 2.99621 ZT20-23 1.6463 1.6463 1.6463