CBS was the most-watched television network for the week ended Dec. 10 among households and younger viewers, airing four of the top 10 programs and maintaining its lead over the other broadcast companies this season, Nielsen Media Research said Wednesday.

ABC was second among households and viewers aged 18 to 49,. NBC was third and Fox was fourth among both viewer groups.

CBS’ “CSI: Crime Scene Investigation,” the most-watched show last year, was also the most-watched show last week, earning an 18.4 rating and attracting 29.8 million viewers. Another of the network’s crime shows, “Without a Trace,” was last week’s No. 3 show, pulling in 19.5 million viewers. “Survivor: Vanuatu” turned up in the fifth spot and the show’s finale tied for seventh.

ABC’s “Desperate Housewives” placed second grabbing 21.6 million viewers and NBC’s “ER” came in fourth with 18.2 million, rounding out the top five shows.

In the ninth week of the television season that began Sept. 20, CBS was ranked first among households, according to Nielsen. NBC is second this year, ABC is third and Fox is fourth.

For the week ended Dec. 12, CBS was watched during prime time in an average of 8.3 percent of all homes with TV sets and 13 percent of those where the TVs where turned on.