You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Doctor_Who

Context:
During the ITV network strike of 1979, viewership peaked at 16 million.[citation needed] Figures remained respectable into the 1980s, but fell noticeably after the programme's 23rd series was postponed in 1985 and the show was off the air for 18 months. Its late 1980s performance of three to five million viewers was seen as poor at the time and was, according to the BBC Board of Control, a leading cause of the programme's 1989 suspension. Some fans considered this disingenuous, since the programme was scheduled against the soap opera Coronation Street, the most popular show at the time. After the series' revival in 2005 (the third notable period of high ratings), it has consistently had high viewership levels for the evening on which the episode is broadcast.

Question:
When was Doctor Who viewing at its highest level?

During the ITV network strike of 1979