condition mean min max ZT0-3 4.9155446125 4.16546201 5.665627215 ZT4-7 3.3537661227499997 2.8108391389999996 3.8966931065 ZT8-11 4.485585120750001 4.2510709040000005 4.720099337500001 ZT12-15 4.05606309925 2.8901937115000003 5.221932487 ZT16-19 5.02603597025 4.2438175065 5.808254434 ZT20-23 7.268135244000001 6.58176169 7.954508798000001