Rush Limbaugh seems to think he knows why Robin Williams died in an apparent suicide earlier this week -- and it's because unhappiness is an attitude of the political left.

The leftist attitude is "one of pessimism and darkness, sadness -- they're never happy, are they?" Limbaugh said on Tuesday's broadcast of his radio show. "They're always angry about something. No matter what they get, they're always angry."

Limbaugh cited a Fox News story that said Williams killed himself because he was embarrassed to take TV roles and parts in movie sequels, but had to do it because of financial troubles.

"He had it all but he had nothing. Made everybody else laugh but was miserable inside," Limbaugh said. "I mean, it fits a certain picture or a certain image that the left has. Talk about low expectations and general unhappiness and so forth."

Limbaugh also read a newspaper report that said Williams felt guilt over surviving the deaths of his friends Christopher Reeve, John Belushi and Andy Kaufman.

"He could never get over the guilt that they died and he didn't," Limbaugh said. "Well, that is a constant measurement that is made by political leftists when judging the country."

While there don't seem to be many studies on political leanings and suicide rates, research published last year found that suicide rates tend to be higher in states that vote Republican and have a higher rate of gun ownership.

A book by James Gilligan, Why Some Politicians Are More Dangerous Than Others, says that suicide and violence rates rise during Republican presidencies and fall during Democratic administrations.

And another study found higher suicide rates in Australia and the United Kingdom when conservative governments are in power.