condition mean min max ZT0-3 3.491495 3.491495 3.491495 ZT4-7 2.513395 2.513395 2.513395 ZT8-11 2.8782750000000004 2.8782750000000004 2.8782750000000004 ZT12-15 3.230785 3.230785 3.230785 ZT16-19 4.039985 4.039985 4.039985 ZT20-23 3.264455 3.264455 3.264455