Ratio of ULPs (CA) filed against employers to petitions filed for union certification (RC), by sector: 1950–1980
| Year | Manufacturing | Retail | Service |
|---|---|---|---|
| 1950 | 0.5 | 0.4 | 0.8 |
| 1953 | 0.5 | 0.5 | 0.6 |
| 1955 | 0.6 | 0.5 | 0.5 |
| 1958 | 0.8 | 0.6 | 0.9 |
| 1960 | 0.8 | 0.7 | 1.1 |
| 1963 | 1.0 | 0.8 | 1.0 |
| 1965 | 1.0 | 1.0 | 1.0 |
| 1968 | 1.0 | 0.9 | 0.9 |
| 1970 | 1.4 | 1.0 | 1.0 |
| 1973 | 1.5 | 1.3 | 1.2 |
| 1975 | 2.2 | 1.5 | 1.2 |
| 1978 | 2.8 | 2.2 | 2.0 |
| 1980 | 3.7 | 2.7 | 2.2 |
Notes: CA cases are charges of unfair labor practices against employers under Section 8(a)1 of the National Labor Relations Act. RC elections are those triggered by workers who are trying to form a union.
Source: National Labor Review Board annual reports, 1950–1980.