Almost 40 Million people tuned in on Saturday to watch Michael Phelps win his 8th Gold Medal.

It was the most watched program on NBC in 18 years. It averaged 31.1 million viewers with an audience peak of 39.9 Million viewers.

NBC is averaging 30.1 million prime-time viewers through the nine days of the Olympics. With swimming over and track and field being almost exclusively tape-delayed it is unlikely that NBC will be able to keep that high of an average…but you never know.