Within the public sector, local government workers had the highest union membership rate at 42.3 percent.

But for several decades now, union membership rates have been declining.

Michigan also has one of the highest union membership rates in the country.

Local government workers—a group that includes teachers, police officers and firefighters—had the highest union membership rate at 43.3 percent.

Nationally, union membership rates for black men in the private sector rose to nearly 40% by the early 1970s.

The occupations with the highest union membership rate included education, training and library jobs.

The chart above shows the private-sector union membership rate since 1973, when it stood at 24 percent, according to data collected at unionstats.com.

"In the absence of federal support for state and local governments, public-sector cutbacks will continue to depress the overall union membership rate," he said.

And public-sector workers had a union membership rate of 37 percent, more than five times that of private-sector workers.

Several African and Latin American countries also had high credit union membership rates, as did Australia.

Members of the Victoria Police (as its officers are generally known) now have among the highest union membership rates of any occupation, at well over 90%.

The union membership rate for public sector workers (36.2 percent) was substantially higher than the rate for private industry workers (6.9 percent).

Overall, union membership rates last year were highest among workers 55 to 64 years old, according the U.S. Bureau of Labor Statistics.

As my colleague Steven Greenhouse wrote on Friday, union membership rates reached a record low in 2010, dipping to 11.9 percent of the American labor force.

The union membership rate for public-sector workers is 36.2 per cent compared with just 6.9 per cent of private-sector workers who are unionised.

New York has the highest union membership rate among states, at just over 24 percent, according to the U.S. Bureau of Labor Statistics.

The majority of union members are now government workers and government workers have a union membership rate of 37 percent, about five times higher than the private sector.

Had union membership rates for women remained at late-1970s levels, racial wage inequality among women in private sector jobs today would be reduced by as much as 30%.

Union membership had been declining in the US since 1954, and since 1967, as union membership rates decreased, middle class incomes shrank correspondingly.

They argue these have led to a trend of declining labor union membership rates and resulting diminishing political clout, decreased expenditure on social services, and less government redistribution.

This reinforced the declining role of trade unions; Hungary's trade union membership rate, currently about 15 percent (the EU average is 25 percent), is also expected to fall.

While France's union membership rate is low, labor unions wield significant influence on government policy and company management in certain sectors, and non-union workers often join strikes and other protests.

Walker campaigned Friday with South Carolina Gov. Nikki Haley, who has called herself a "union buster" and considers her state's low union membership rate an economic development tool.

That’s because of the differing unionization rates in the two sectors: The union membership rate for government workers (36.2 percent) was more than five times the rate for private sector workers (6.9 percent).

About a quarter of voters in Michigan — home to one of the highest union membership rates in the country — said they or someone in their household belonged to a labor union.

The challenge of increasing union density from the present 20% to beyond 30%.

Union density actually declined in the past year, though only slightly.

Among the 10 major occupational groups, union density rose in 6.

"These are also areas where union density is among the highest anywhere in the nation."

This helps explain the greater stability of union density among women.

Only the Scandinavian countries have a higher labor union density.

The overall union density ratio has remained within the 31-to-33 percentage range.

Trade union density figures are provided below for various countries:

Canada, which does have card check elections, has seen union density fall by almost 10 points since the mid-’80s.

A broad range of forces have been identified as potential contributors to the drop in union density across countries.

The prevalence of unions in various countries can be assessed using the measure "union density".

Union density in each of these industries was also above the Canadian average (Table 2).

Only in the Nordics has union density been maintained.

But it's far more revealing to look at changes in union membership as a portion of potential members, a figure called "union density."

However, for youth unemployment and long-term unemployment our results show a negative effect of trade union density.

It is not surprising that income inequality has grown as union density has declined.

The paper analyzes forces driving union density since the mid 1980s, using household survey, administrative and public opinion data.

Workers in both permanent and non-permanent jobs recorded increases in union density.

Clearly, the resources needed to support these good practice measures have become scarcer as union density rates have fallen.

Note: Union Density is the proportion of the active labour force organized into trade unions.

Globalisation has reduced workers" bargaining power around the world; union density rates have fallen internationally.

Indeed, stability in the public sector prevented overall union density in Canada from falling below 30%.

Figures from South Africa show that union density for younger workers in 1999 was less than half that of older age groups.

The figures often used in public debate measure trade union density against the number of employees in employment plus the unemployed.

The definition of union density is "the proportion of paid workers who are union members".