SAN FRANCISCO, Dec. 28 (Xinhua) -- Facebook CEO Mark Zuckerberg said Friday that he felt "proud of the progress" the company has achieved in 2018, despite having gone through a tumultuous, scandal-plagued year.

Zuckerberg said in a year-end post that Facebook has "fundamentally" changed to focus on keeping its services safe and protecting them against manipulation and misinformation.

"We're a very different company today than we were in 2016, or even a year ago. We've fundamentally altered our DNA to focus more on preventing harm in all our services," Zuckerberg said.

He admitted that for the past year, his company has been grappling with a host of tumultuous incidents and challenges that have put the world's largest social media network under close scrutiny of U.S. legislators, regulators and the public.

Those challenges ranged from the alleged Russian interference in the 2016 U.S. presidential elections, the April scandal involving Cambridge Analytica, a British political consulting firm that was accused of illegally harvesting the private data of about 87 million Facebook users without their knowledge, to an October hacker attack that exposed the email accounts, phone numbers and birthdays of more than 30 million people.

"Addressing these issues is more than a one-year challenge," Zuckerberg said.

To ensure Facebook's services are safe, Zuckerberg said that his company has deployed 30,000 people to work on the social media giant's safety and invested billions of U.S. dollars in security every year.

"That doesn't mean we'll catch every bad actor or piece of bad content, or that people won't find more examples of past mistakes before we improved our systems," said the Facebook CEO.

He disclosed that Facebook has "built some of the most advanced systems in the world" for identifying and detecting those problems.

In order to stop the spread of harmful content, "we've built AI systems to automatically identify and remove content related to terrorism, hate speech, and more before anyone even sees it. These systems take down 99 percent of the terrorist-related content," Zuckerberg said.

"I'm also proud of the rest of the progress we've made this year. More than 2 billion people now use one of our services every single day to stay connected with the people who matter most in their lives," he wrote in Friday's post.