The NYT has a bunch of interesting charts on this. But suffice it to say that high-level managers appear to have become much more skilled at directed value into their own pockets:
What I always wish I could see more of were direct international comparisons. Not only do high-paid oil and gas CEOs all get paid roughly similar amounts of money despite drastically different performances, but running a large American oil company is much more lucrative than running the giant French oil company. Anglophone firms just pay CEOs much more than continental European firms or Japanese firms. Meanwhile, though pretty much all firms are happy to discover and apply some new methods to hold down labor costs you rarely if ever see a firm bragging about its success in reducing executive compensation.