SAN FRANCISCO – Google is disclosing how much of the traffic to its search engine and other services is being protected from hackers as part of its push to encrypt all online activity.

Encryption shields 77 percent of the requests sent from around the world to Google’s data centers, up from 52 percent at the end of 2013, according to company statistics released Tuesday.

The numbers cover all Google services expect its YouTube video site, which has more than 1 billion users. Google plans to add YouTube to its encryption breakdown by the end of this year.

Encryption is a security measure that scrambles transmitted information so it’s unintelligible if it’s intercepted by a third party.

Google began emphasizing the need to encrypt people’s online activities after confidential documents leaked in 2013 by former National Security Agency contractor Edward Snowden revealed that the U.S. government had been vacuuming up personal data transferred over the Internet. The surveillance programs exploited gaping holes in unencrypted websites.

While rolling out more encryption on its services, Google has been trying to use the clout of its influential search engine to prod other websites to strengthen their security.

In August 2014, Google revised its secret formula for ranking websites in its search order to boost those that automatically encrypted their services.