I think there is a union floor you can’t go under. Face it some unions will not go away, ever. So I think we are pretty close to zero union for all practical purposes.
Nope, too many public sector unions.
“Public-sector workers had a union membership rate (35.7 percent), more
than five times higher than that of private-sector workers (6.6 percent).
(See table 3.)
—Workers in education, training, and library occupations and in protective
service occupations had the highest unionization rate, at 35.3 percent for
each occupation group. (See table 3.)”
http://www.bls.gov/news.release/union2.nr0.htm