LOS ANGELES - Fewer American households own a television set in 2010, representing the first reduction in 20 years, Nielsen Co. said on Tuesday.

The overall estimates of American homes which own a TV set totaled 114.7 million, down from 115.9 million from previous year, or a decline to 96.7 percent from 98.9 percent, Nielsen said, basing its estimates on the 2010 US Census.

This is the first time since 1992 when a decline was first registered, which has since been followed by a significant growth, the company said.

Driving the downward trend are several potential factors, the global marketing and advertising research company said. These include a shift from analog to digital broadcasting in 2009, a dismal economy which has seen consumers, especially those with lower incomes or living in rural areas, had to give up their television-watching habits.

Watching television on a computer or tablet device is getting more popular, the company said.

In addition, more and more people, with urban consumers in particular, have access to video content across a variety of platforms including mobile devices and online, and many chose to stop subscribing to paid TV programs, according to Nielsen.

Pat McDonough, Nielsen's senior vice president of insights and analysis, said this last factor is leading the company to change how it measures audiences in the future.

"Nielsen' s cross-platform media strategy will allow us to measure all of this content and report the total picture of video consumption to our clients regardless of delivery method," he said.  "As the census data shows that we are a more diverse country, our measurements evolve to reflect our diversity and also to encompass all the ways that Americans consume media."