In 1901 transport and office workers came to be covered by public health insurance, followed in 1911 by agricultural and forestry workers and domestic servants, and in 1914 by civil servants. Coverage was extended to the unemployed in 1918, to seamen in 1927, and to all dependents in 1930. In 1941 legislation was passed that allowed workers whose incomes had risen above the income ceiling for compulsory membership to continue their insurance on a voluntary basis. The same year, coverage was extended to all retired Germans. Salespeople came under the plan in 1966, self-employed agricultural workers in 1972, and students and the disabled in 1975.