About 51.4 million people watched Vice President Biden’s jocular debate Thursday with the GOP veep candidate, Rep. Paul Ryan (Wis.), across 12 TV networks — 10 of them live at 9 p.m.

Sure, that’s about 18 million fewer than watched the ’08 veep debate. But that debate, in which Biden squared off with Alaska’s then-Gov. Sarah Palin, was epic.

Thursday’s lively back and forth, moderated by Martha Raddatz, ABC News’s senior foreign affairs correspondent, was one of the better-watched veep debates. Except for Biden-Palin, it clocked the biggest audience since the ’84 faceoff between George H.W. Bush and Geraldine Ferraro, which logged 56.7 million viewers.

On Thursday, nearly 27 million viewers were 55 and older. Just 7.2 million were ages 18 to 34.

The Nielsen stats include viewing on ABC, CBS, CNBC, CNN, Current TV, Fox, Fox News, MSNBC, NBC and PBS as well as tape-delayed coverage on Telemundo and Univision.

About 10 million debate-watchers went with Fox News, the biggest audience of any network covering the event.

CBS (8.31 million viewers) was its closest competitor, followed closely by ABC (8.29 million). NBC trailed with 7.85 million.

On the bright side, NBC’s coverage of Biden vs. Ryan seems to have done 45 percent better among advertiser-preferred 18-to-49-year-olds than the network’s programming the previous Thursday in that same 90-minute block of time: “The Office,” “Parks and Recreation” and “Rock Center.”

Sadly, the debate is a “sustained” program for the broadcast networks, which means the ratings don’t count and aren’t included in their season, weekly or time-slot averages.

Fox brought up the rear among commercial English-language broadcast networks, with an average of 5 million tuned in.

Fox News’s total beat CNN (4.2 million) and MSNBC (4.4 million) combined.

For previous columns by Lisa de Moraes, go to washingtonpost.com/