Task: Question Generation
Input (English): The structure of the Swiss militia system stipulates that the soldiers keep their Army issued equipment, including all personal weapons, at home. Some organizations and political parties find this practice controversial but mainstream Swiss opinion is in favour of the system. Compulsory military service concerns all male Swiss citizens; women can serve voluntarily. Men usually receive military conscription orders for training at the age of 18. About two thirds of the young Swiss are found suited for service; for those found unsuited, various forms of alternative service exist. Annually, approximately 20,000 persons are trained in recruit centres for a duration from 18 to 21 weeks. The reform "Army XXI" was adopted by popular vote in 2003, it replaced the previous model "Army 95", reducing the effectives from 400,000 to about 200,000. Of those, 120,000 are active in periodic Army training and 80,000 are non-training reserves.
Output (English): Who can serve in the Swiss military voluntarily?