condition mean min max ZT0-3 20.208738333333333 8.166165 28.27275 ZT4-7 8.349120000000001 8.349120000000001 8.349120000000001 ZT8-11 11.60875 11.60875 11.60875 ZT12-15 16.296750000000003 14.70345 17.890050000000002 ZT16-19 18.59355 18.59355 18.59355 ZT20-23 28.24695 28.24695 28.24695