What are the primary airports that present in Italy during the year 2004 ?
These categories account for over 15 % of AIP - funded airports in the U.S. Primary airports are further subcategorized into : Nonhub primary – airports handling over 10,000 but less than 0.05 % of the country 's annual passenger boardings Small hub primary – airports with 0.05 to 0.25 % of the country 's annual passenger boardings Medium hub primary – airports handling 0.25 to 1 % of the country 's annual passenger boardings Large hub primary – airports handling over 1 % of the country 's annual passenger boardings A third major category contains reliever airports , which are essentially large general - aviation airports located in metropolitan areas that serve to offload small aircraft traffic from hub airports in the region .