CNN’s Republican presidential debate, moderated by Wolf Blitzer, averaged 18 million total viewers, with 5.6 million in the 25-54 demo.

The debate—featuring Ted Cruz, Carly Fiorina, Marco Rubio and others, including, of course, Donald Trump—represented the second most watched program in CNN history. It trailed only a debate in September that gathered 23.1 million viewers.

The Dec. 15 event happened in Las Vegas. Streaming live on CNN.com and the cable net’s mobile apps and connected TVs, the program tallied 3.1 million live streams.

According to CNN, seven of the top 10 presidential primary debates in terms of TV ratings have occurred in 2015, led by the Fox News GOP tussle in Cleveland in August, with nearly 24 million total viewers.