You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "when did penn st join the big ten?" whose answer is 1990.
Each document should contain about 30 words, and these documents should contain useful information.

Query: when did penn state join the big ten
Useful Output:

Doc 1: On June 4, 1990, the Council of Presidents officially voted to integrate Penn State into the conference, giving the Big Ten 11 members.
Doc 2:  Big Ten name did not become official until 1987.  For 41 years, the Big Ten remained unchanged, but in 1990, Penn State joined the conference.
Doc 3: 2.1 Early history · 2.2 1940s: Chicago leaves and Michigan State joins · 2.3 1990 expansion: Penn State · 2.4 2010–2014 expansion: Nebraska, Maryland, Rutgers. 2.4
Doc 4: After a long and storied history as a college football independent, Penn State joined the Big Ten Conference in 1993, going 10-2 (6-2) under
Doc 5: In joining what was known as the Western Conference when it was formed in Chicago by seven colleges in 1895, Penn State, in State College, Pa.,