Although online advertising growth is slowing, it will grow 19.5 percent on average each year until 2012, representing the highest growth levels of media around the world, according to PricewaterhouseCoopers' annual Global Entertainment and Media Outlook, paidContent reported Wednesday.

In general, PwC predicts global ad revenues will reach US$2.2 trillion by 2012, growing an average of 6.6 percent each year.

PwC predicted last year that online advertising and access spending would grow at about 13.4 percent through 2011, and from 2006 to 2007, it grew 37.9 percent, paidContent reported.

In addition to Internet growth, digital's market share is expected to remain small, accounting for 24 percent of overall industry growth through 2012, when digital and mobile revenues are expected to account for 11 percent of total entertainment and media spending, PwC has forecast, according to paidContent.