53 ships over 1,000 gross tons were in the Australian fleet in 2006. The use of foreign-registered ships to transport Australian cargoes between Australian ports is permitted under a permit scheme, with ships receiving either a Single Voyage Permit (SVP) or a Continuous Voyage Permit (CVP). Between 1996 and 2002, approximately 350 percent more permits were issued to ships. In recent years, the number of Australian-registered and flagged ships has significantly decreased; from 75 ships in 1996 to fewer than 40 ships in 2007, the number is now There have also been instances in which locally operated ships have an Australian flag from the vessel, registering it overseas under a flag of convenience, and then hiring foreign crews who earn up to about half the monthly rate of Australian sailors. These moves were supported by the Howard government but opposed by maritime unions and the Australian Council of Trade Unions. The registration of the ships overseas also meant the earnings of the ships are not subject to Australian corporate taxation laws. Marine unions blame the decline on the shipping policy of the Howard