Since 1849 Danish military defense has been based on compulsory national service. All young men must register at the age of 18 and are subject to 9–12 months service. Voluntary military service is popular because of educational benefits. Total active armed forces numbered 22,700 in 2002, including 685 women. The army consisted of 12,800 personnel, the navy 4,000, and the air force 4,500. There were also 64,900 members of the reserves and 61,500 in the volunteer home guard. Danish forces participated in UN and peacekeeping missions in 14 regions around the globe, and provided support for Operation Enduring Freedom. Military expenditures for 2000 amounted to $2.5 billion or 1.4% of GDP.