During the ongoing antitrust trial in Washington, the main economics expert disclosed this number, saying that Apple Inc. (AAPL  ) receives 36% of Alphabet Inc.'s (GOOG  ) (GOOGL  ) search revenue made via the Safari browser.

What Happened: Kevin Murphy, a University of Chicago professor and key witness for Google, on Monday made these revelations, which made John Schmidtlein, the tech giant's main litigator, visibly cringe, as it was supposed to remain confidential, reported Bloomberg.

According to the report, both Google and Apple had previously objected to public disclosure of specifics regarding their agreement.

In a court filing last week, the search and advertising giant argued that making additional information about the agreement public would "unreasonably undermine Google's competitive standing in relation to both competitors and other counterparties."

Apple and Google have had this partnership since 2002, making the latter the default search engine in Safari. Moreover, the deal's significance has increased because it sets the default search engine on iPhone.

According to Statista, a German database company, last year, more than 120 million people in the U.S. had iPhones, making them 49% of all smartphone users in the country.

Why It's Important: The DOJ has accused Google's search division of maintaining a monopoly in the market via annual payments of $10 billion to make its search engine the default choice on mobile devices and web browsers.

Earlier this month, when Google CEO Sundar Pichai testified, he justified these payments, saying they were to create a "seamless and easy" user experience.

It is pertinent to note that if the Pichai-led company is found guilty of breaking the law, another trial will commence and determine how to curb its market power.

Losing this trial could potentially halt Google's practice of paying out Apple and other companies.