Shipments of LCD flat-panel TVs will fall this year from the year before, the first such decline since the popularity of such TVs took off in 2006, according to a research firm.

Lingering economic concerns and slow price declines will crimp shipments to 31.9 million sets this year, iSuppli said. That’s down 1.2 percent from 2009.

Apart from the economy, it’s possible U.S. consumers are finally having their appetite for new TVs satisfied. The Consumer Electronics Association says about two-thirds of households now have high-definition sets.

LCD is the most popular type of TV, accounting for more than 90 percent of U.S. sales. In January, the CEA projected the industry would sell 37 million sets this year, including plasma TVs.

Prices have come down this holiday season after remaining relatively stable earlier in the year. Some stores are selling 32-inch LCD TVs for $200, less than the long-run average of TV prices in the U.S. Because of the price declines, annual revenue from TV sales started shrinking in 2009.