I would suggest that employee free choice has driven down the unionization levels in the world.
The greatest decline has come in Europe where it has been made illegal to have forced membership. Suddenly everyone started leaving the union, because they were allowed to do so easily. It has been stabilizing through increased efforts by Unions to be attractive vehicles for better working conditions. in short, unions are back doing what they are supposed to do, represent workers, not political goals.
Australia is an excellent example, the employees are getting a better deal now because the unions are trying to work for the members, not the executive.
I am working today but I have a lot of research available about this CatLady, it is *very* interesting and it does *not* point to employer involvement, it points to employees who use the courts to fight their way out of Unions.
The AFL-CIO is not the bastion of moderation when viewing such news at reduced global union density.
Find - Desiderata - read it