If you look at the chart below you'll see that labor's share of the economy was pretty steady for the 40 years from 1940 to 1980.
Then came Reagan and "trickle down" economics. That's when labor's share of national income started to drop precipitously.
Corporate profits, on the other hand, rose slowly, but steadily from 1940-1980. When Reagan took office corporate profits started to surge and with the exception of the recent, short, correction during the Great Recession, corporate profits have been skyrocketing while labor's share has been plunging.
What is the explanation for this? It is simply, that the Reagan era ushered in massive deregulation, assault on social programs, huge tax cuts for the rich, outsourcing and union busting, all of which decimated the real earnings of the working class.
While corporations have gotten a greater and greater share of national income and wealth, workers have seen their portion stripped away. All by design.
What's REALLY interesting, though, is how extreme this trend has become under Obama. We have never seen a period of such rapid wealth accumulation by the corporate sector and such rapid wealth destruction of the working class as we have under Obama. This again suggests that claims Obama is "anti-business" are completely hollow.