TF1 ruled over French TV ratings in 2008. But the Gallic broadcaster took a huge hit from digital terrestrial TV, which truly came of age this year in Gaul.

Net’s total audience share plunged 2.5 percentage points from 30.7% in 2007 to 27.2% for 2008, according to French audience research company Mediametrie, surveying weeks Dec. 31 2007-Dec. 28, 2008.

France’s other broadcast networks also dropped in share, but less dramatically.

M6 edged down just 0.5 points to 11%.

Pubcaster France Televisions also enjoyed a smoother ride. FT’s core channel France 2 dipped from 18.1% in 2007 to 17.5% this year, its cultural service France 3 from 14.1% to 13.3%.

Analysts blame DTT for the nets’ rating erosion. DTT audience share rose spectacularly from 2007’s 17.5% to 23.7% for 2008, and 26.3% in December.

“TF1 had more share to lose,” said Bertrand Villegas, at Paris-based audience analysis company The Wit.

“TF1’s mainstream family target favors interest in DTT. Cable and satellite are more popular in higher income groups. M6 skews younger, and FT older in audiences,” Villegas added.

Though TV ratings for movies are plunging in many countries, two French films, both comedies, ranked among top-rating TF1 fiction: “Les Bronzes 3: Amis pour la vie” (47.4%) and “Les Bronzes font du ski” (37%)

France 2 was boosted by “Without a Trace” (30%) and Gallic costume drama series “Chez Maupassant” (26.5%); France 3’s top fiction performer was long-running soap, “Plus belle la vie” (24.9%).

M6 was bulwarked by sharing the Euro 2008 soccer tournament with TF1 and boasted the most-watched program of 2008.

As over much of Europe, that was soccer: France’s crunch first-round decider against Italy in Euro 2008. An average 13.2 million viewers, for a 47.8% share, saw France lose, albeit with honor.