What does the literature say about proportional representation and economic performance?

Many of the world's most productive countries use a form of proportional representation when electing politicians, which can dramatically change how the government functions and the policy choices it makes. Finding concrete proof that there is a causal link between PR and economic performance is, I imagine, very hard to do, further complicated by the fact that there are many different PR systems. That said, is there any literature that goes beyond mere correlation and tries to find a causal link? What are the findings?