The Games averaged 20.2 million viewers in prime time on NBC, according to Nielsen Media Research.
Thursday's coverage, featuring the women's figure skating finals (25.7 million), was the biggest night while Sunday's closing ceremony (14 million) was the lowest.
Several factors are said to have contributed to the decline: taped coverage for which results were easily available online; a shortage of emerging stars (and poor performances); a record amount of coverage spread among cable networks; and aggressive counter-programming.
NBC finished second or worse on five of 17 nights among all viewers and on seven nights among young adults.
However, the Olympics still remain a powerful draw, winning most nights - and the past two weeks - for NBC.
