Internet display advertising expenditures reached $2.31 billion in the first quarter - a 19.4 percent growth over the year-ago period, according to TNS Media Intelligence, writes ClickZ. That was the highest rate of growth for all media forms. Overall advertising growth was only 5.2 percent for the same period, reaching $34.9 billion.

An earlier TNS forecast for all of 2006 anticipated internet display ad growth at 9.1 percent, whereas the 5.2 percent growth of all advertising in the quarter is just short of the 5.5 percent forecast for the full year.

For the quarter, the Top 100 companies, as ranked by total measured ad expenditures, accounted for 34.7 percent of all internet display spending. Internet companies accounted for 50.1 percent of spending in the category - "that's the highest percent of dot-com activity since the bust in 2001," according to TNS SVP of Research Jon Swallen.

TNS provides details of ad spending by media, advertiser and category, as well as additional information, here.