The rate of unionization in America fell from 12.5% to 12.0% in 2006 according to the Bureau of Labor Statistics
The union membership rate for government workers (36.2 percent) was substantially higher than for private industry workers (7.4 percent). Within the public sector, local government workers had the highest union membership rate, 41.9 percent. This group includes several heavily unionized occupations, such as teachers, police officers, and fire fighters. Among major private industries, transportation and utilities had the highest union membership rate, at 23.2 percent, followed by construction (13.0 percent). Within the information industry, telecommunications had a 20.7 percent union membership rate. Financial activities had the lowest unionization rate in 2006--1.9 percent.
I would have guessed manufacturing was higher than the reported 8%. This puts in rather stark relief the relationship between the Democrats and unions -- it's actually the relationship between government workers and their paymasters.