Online ad revenues increased 14% year-over-year in the first half (H1) of this year, according to [pdf] the latest revenue report from the Internet Advertising Bureau (IAB) and PricewaterhouseCoopers (PwC). That brought H1 revenues to a record total of $17 billion, from$14.9 billion in H1 2011. Q2′s $8.7 billion in revenue makes it the largest quarter on record save for Q4 2011 ($9 billion), and itself represents a 14% year-over-year gain. Looking back to 2003, Q2 revenues have grown at a brisk compound annual rate of 20.2%. Still, that growth is more muted when factoring in inflation, as well as the growth of the online audience. A recent MarketingCharts analysis of IAB data showed that online ad spend per user, in constant dollars, has risen by roughly 50% between 2000 and 2011 (from $67 to $100), and has grown by slightly less than 3x since 2002.