Does anyone have any idea how much traffic Bing gets from their integration in the facebook search? Would be interesting to know on what scale they are already

Does anyone have any idea how much traffic Bing gets from their integration in the facebook search? Would be interesting to know on what scale they are already capturing this type of intent & relevance search traffic. I'm guessing from the fact they integrated web search back in 2008, and it's not been made more prominent since, not a huge amount.