Plain As Day
There it is in black and white. As the percentage of workers in unions has gone down so has our share of the pie. That's all of our share, because unions kept wages up for everyone. If there were good union jobs available, non union employers had to come pretty close to matching them in wages and benefits just to get people to work for them.
Unless you want to pass on a country to the next generation where workers are powerless and make third world wages, if you're not agitating to do something about things like this you're wasting your time.