The advertising-supported Internet "ecosystem" generated $530 billion last year and supported 5.1 million jobs in the United States, an industry study said Monday.

The study released by the Interactive Advertising Bureau said the economic value of online industries has roughly doubled since 2007.

Researchers from the Harvard University Business School commissioned by the IAB, said this amounted to 3.7% of the U.S. gross domestic product last year, up from 2.1% four years ago.

"The substantial economic impact of the Internet -- through its evolution and dynamism -- has been borne out by this study," said study author John Deighton.

"Once accessed only from large desktop machines that connected the office or home to the world, the Internet, thanks to mobile phones and tablets, has become ubiquitous."

The report, "Economic Value of the Advertising-Supported Internet Ecosystem," was unveiled at the annual IAB conference to quantify the significant role the ad-supported digital sector plays in the broader U.S. economy.

The report shows New York and California as home to the headquarters of the largest number of U.S. Internet firms.