condition mean min max ZT0-3 34.895245 34.895245 34.895245 ZT4-7 21.3909735 21.3909735 21.3909735 ZT8-11 16.720556000000002 16.720556000000002 16.720556000000002 ZT12-15 15.980712 15.980712 15.980712 ZT16-19 15.677305 15.677305 15.677305 ZT20-23 17.914326000000003 17.914326000000003 17.914326000000003