According to a story in MediaPost.com,  Citigroup estimates online advertising will grow 21% this year, up from 15% in 2010.

Citibank estimates online advertising will grow 17% in 2012 and 14% in 2013.

“Search will grow more rapidly than online advertising, taking share during the next few years, he said. Growth in display will follow behind search advertising and come from social and digital video ads.”

“If more TV advertising comes online, the 14% and 17% growth estimates for the next two years will become conservative, and the industry could see about 20% growth.”

The article goes on to say that social media sites maybe the biggest beneficiary growth.

According to a Citibank poll of marketing executives, “65% said they will spend more in social media, 50% in Web site upgrades, 53% in content creation, 51% in landing page optimization, 49% in search engine marketing for both SEO and paid search, 42% in online advertising, 42% in email, and 15% in direct mail.”

“Facebook now constitutes more ad impressions than Yahoo, Microsoft and AOL combined,”