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 the salary cap start in the nba?" whose answer is 1984–85 season.
Each document should contain about 30 words, and these documents should contain useful information.

Query: when did the salary cap start in the nba
Useful Output:

Doc 1: The cap is set by the league and is typically based on a percentage of the league's overall revenue from the previous season. This is designed
Doc 2: Each year, a new cap is established based on the earnings from the previous season and the Collective Bargaining Agreement. This is a contract
Doc 3: The first salary cap season was in the 1940s, but it was in place for only one season. The league reinstated the salary cap structure in the
Doc 4: It's spring 1983, and the New York attorney representing the players union with NBPA executive director Larry Fleisher and union president Bob
Doc 5: The salary cap is a set amount of money designed to limit what teams can spend on player payroll. The number is determined for each season.