• by Wayne Friedman , March 25, 2010

Hit by NBC's Vancouver Winter Olympics, ad-supported cable ratings took a rare dip in the first quarter among the key 18-49 viewer group.

According to data released by Turner Broadcasting -- by way of Nielsen -- cable dropped 2% among 18-49 viewers to an aggregate 17.6 rating in prime time through March 21.

The last time this happened to cable was in first-quarter 2006, when NBC broadcast the Torino Winter Olympics. Cable also dropped 2% then.

All this didn't seem to help the collective four network ratings during the period. Their ratings were down 1% to a 12.0 number. In 2006, the numbers showed a rare rise -- 2% -- to a 15.0 rating.

Still, the broadcast networks gained in share among 18-49 viewers during the period, up 2% to a 31.9 share. Ad-supported cable was flat to a 47.3 share.

Another uncommon occurrence for cable: it is also down slightly -- 1% -- in season-to-date prime-time ratings through March 21, to an 18.0 number.

The four broadcast networks are also down for the year -2%. The good news for broadcast is that it is somewhat lower than in previous years -- down 4% in 2009 versus the previous year. It was down 10% in 2008 versus 2007.

The report also notes that in the first quarter some of cable's highest-rated shows gained significantly through time-shifted viewing.

In looking at live plus seven days of time-shifting viewing, USA's "Burn Notice" rose 56% to 6.4 million viewers; USA's "Psych" was up 58% to 4.4 million; TNT's "Leverage" climbed 65% to 4.4 million; and Lifetime's "Project Runway" witnessed an 80% improvement to 3.8 million.

Among key 18-49 viewers, the gains are even more prominent: "Burn Notice" climbs 71% to 3.2 million 18-49 viewers when including seven days of time-shifted viewing; "Project Runway" gets more than double its live airing from time-shifted viewing -- 109% -- to 1.3 million of its 2.2 million total; and "Psych" climbs 80% to 2.2 million.