A report by SNL Kagan said it expects U.S. mobile game revenues to top $1.53 billion this year, which is nearly double revenues in 2010. At that amount, the mobile industry will make up about 7.7 percent of the $20 billion U.S. games market.

Looking further out, SNL Kagan anticipates mobile game revenues to top $7.81 billion in the next decade.

The author, John Fletcher, identified this year’s fourth quarter as a key turning point as consumers download new apps after receiving a smartphone as a gift during the holiday season. During the final three months of the year, he expects U.S. mobile game publishers to generate more than $439.4 million, up 62 percent from $271.7 million in the prior-year period.

He said the revenue growth is being driven by the free-to-play model, which enables publishers to make more than if they were charging 99 cents. While only a few customers actually make in-app purchases, they easily outspend the number of people willing to spend 99 cents on a game they don’t know if they will enjoy.

As the freemium model prevails, he expects newcomers, including Zynga, will make a dent in the space by the fourth quarter. However, Fletcher anticipates incumbent companies, like Electronic Arts and Gameloft, will continue to dominate.

Here’s a list of the Top 10 based on estimated fourth-quarter revenues:

1. EA Mobile
2. Gameloft
3. Ngmoco (owned by DeNA)
4. Rovio Mobile
5. Glu Mobile
6. Capcom
7. Zynga (acquired Newtoy)
8. Sony Pictures Mobile
9. Namco Bandai
10. MocoSpace