Union membership of wage and salary workers, selected occupations, 2005 Occupation Percent Ed., training, and library 38.5 Protective service 37.0 Trans. and material moving 19.0 Construction and extraction 17.6 Installation, maint. and repair 17.2 Production 17.1 Community and soc. services 16.5 Farming 3.9 Sales and related 3.3