LOS ANGELES — PBS’ average prime-time household rating for the 2013-14 season was up 5 percent over the year before, the public TV service said Wednesday.

Among all broadcast and cable networks, PBS said it ranked fifth in the Nielsen audience measurement, compared with eighth for the previous season and 11th for 2011-12.

Two prominent families, the Roosevelts and the Crawleys, helped. Ken Burns’ documentary series “The Roosevelts: An Intimate History,” and season four of “Downton Abbey” aired during the 12-month period.

“The Roosevelts” earned PBS its biggest audience in two decades, while British drama “Downton Abbey” ranked as the highest-rated drama in public TV’s history. The British soap opera returns Jan. 4.

Beth Hoppe, PBS’ chief programming executive, said the audience growth also reflects a strong overall schedule.