After a year in which CNN sank to an all-time low in prime-time viewership, CNN Worldwide chief Jeff Zucker wrote in a memo to the network’s staffers that CNN has “had a really good year” in 2013, Deadline.com reports.

But Zucker added in the memo that “there is much more to do,” the report notes.

Zucker highlighted the addition of Anthony Bourdain’s show and the success of the documentary “Blackfish,” but didn’t mention the network’s new morning program, "New Day," or the relaunched “Crossfire,” the story notes. Both programs have had less than spectacular ratings rollouts.

“Real change that transforms an organization doesn’t happen overnight," Zucker wrote. "I have talked a lot about broadening the definition of news. You have seen the start of that, especially at CNN, where we have begun to introduce new series, documentaries and films to augment our best-in-class breaking news coverage."

Zucker’s memo adds: “Competitively speaking, there is much to be proud of. CNN Digital had its best year, EVER. In almost every measurement, CNN’s digital properties, domestically and internationally, hit record highs. HLN was the only domestic cable news network to grow its audience this year, up double digits across the board. CNN moved from the third most watched cable news network in 2012 to second in 2013.”