According to a report released yesterday, by the Interactive Advertising Bureau and PricewaterhouseCoopers, online advertising last year reached $23.4 billion, with the 4th quarter total of $6.1 billion up 2.6% from the 4th quarter of 2007.

The 2.6% increase in 4th quarter ad revenue, was the smallest since 2002. The 51% of total online ad dollars spent during the second half of 2008 was also the lowest percentage for the last six months of any year since 2002.

In all online advertising growth was cut by more than half last year to 10.6%.

“””And with online ad growth all but stalled in 2008 and the near-term outlook on the economy not improving, some experts have gone from predicting flat-to-slow growth in 2009 to a decline.

At least week’s OMMA Global Hollywood conference, economist Dr. Paul Kedrosky projected online ad dollars would fall 8%-9% in 2009, with traditional ad spending falling even farther amid a slumping GDP.”””

On a bright note, search increased its share of online advertising to 45% from 41% of online advertising in 2008.

Likewise, performance-based advertising overall jumped to 57% from 51% of online ad dollars.