So who is winning in the mobile ad business?

Never mind the fact that nearly 40 percent of mobile ad clicks are either accidental or fraudulent — the folks from eMarketer say that mobile ad revenues in the U.S. will grow from $1.45 billion in 2011 to $6.62 billion in 2014.

The New York-based research group projects that by 2016, the U.S. mobile advertising market will be close to $12 billion. It should not come as a surprise that search-and-advertising giant Google, which also owns Android OS, will continue to dominate the industry and will grow at a monster speed. However, Pandora and Twitter stand out for their mobile ad revenues. While Twitter is beating Facebook as of now, it won’t be long before Facebook makes a comeback and takes about 9.5 percent of the market in 2014. Apple’s (a AAPL) iAd continues to struggle and perhaps it is time for Apple to rethink its ad foray and instead go back to its knitting.