The number of trade unions in New Zealand has varied dramatically as labour laws have changed. From a tiny total in the 19th century, the number reached a peak of 500 in the late 1930s, when union membership became compulsory. Unions dropped to a 20th-century low of fewer than 100 after compulsory unionism was abolished in 1991 by the Employment Contracts Act, before rising slightly again following the repeal of the Act in 2000.