The phrase "a viewership of" is correct and usable in written English.
You can use this phrase when talking about the size of an audience watching something, such as a television show. For example, "The season finale of the show attracted a viewership of over 10 million viewers."
On a recent week, it finished third, behind reruns of "Two and a Half Men" and "Family Guy," with a viewership of about 4.9 million people.
When final ratings are in the Oscars should have a viewership of about 42.5 million, estimated Larry Hyams, ABC's chief researcher.
"The Parkers," currently the highest-rated African-American show, has a viewership of about 5 million (primarly in black homes), less than half of the numbers posted by "Dharma and Greg".
CBS Evening News, which under Cronkite overshadowed the rival programmes at NBC and ABC, had a viewership of some 20 million, almost as much as the combined audience of the three shows today, when the national population is half as large again.
But organizing grassroots demand for the Outdoor Channel has helped build a viewership of 14 million for the Temecula, Calif.-based network.
The Toonami block averaged a viewership of 3.8 million during 2001, which means the Nintendo promotion drove nearly one-third of the Cartoon Network's audience online.
The series received a viewership rating of 23.9% for its last episode, and an average rating of 15.48% for its entire run.
It received a viewership peak of 1.2 million with its final episode, giving it an audience share of 8.9 per cent.
And "Revolution" did lose some viewers at its half-hour mark, falling to a 3.8 rating from a 4.4, and to a total viewership of 11 million from 12.3 million.
It premiered in 122 countries in thirty-five languages, with a total viewership of 10 million and an average rating of 2.0 in most metered television markets.
The episode was later beaten by the season finale, "A Canterlot Wedding" parts one and two, which scored a total viewership of 483,000 and 475,000 respectively.
