It's funny because that question is answered every time the difficulty changes. Maybe these people could use the search function once in a while, you know...
Have you tried it?
Give me a search phrase that can answer this question without browsing beyond the 3rd page of results.
My first hit, after looking for 2 minutes:
search "network hashing", match any words, check search in topic subjects only, limit it to the mining sub section. Only one page of results, 3rd from the bottom. Thread if from February.