Joe Biden was the biggest star.An estimated 38.2 million people watched him deliver his first State of the Union speech last week, spread across several networks that carried it. Fox News Channel, where 7.2 million people watched, had the biggest single audience, the Nielsen company said.Otherwise, no prime-time program exceeded 8 million live viewers. On a typical night, ABC's “World News Tonight” with David Muir had a bigger audience than anything else on TV last week.Among individual prime-time shows, “60 Minutes” finished on top for the second week in a row, Nielsen said.CBS won the week in prime time with an average of 4.6 million viewers.