condition mean min max ZT0-3 3.24269 2.890905 3.9221700000000004 ZT4-7 3.3836500000000003 3.3836500000000003 3.3836500000000003 ZT8-11 3.86446 3.86446 3.86446 ZT12-15 3.6596475 3.60623 3.7130650000000003 ZT16-19 4.564265000000001 4.564265000000001 4.564265000000001 ZT20-23 3.462615 3.462615 3.462615