As the summer begins to wind down, “The Late Show with Stephen Colbert” has shown no signs of slowing down in the ratings.

According to Nielsen data from May 25 to Aug. 13, Colbert is averaging a 0.53 rating in the key adults 18-49 demographic and 3.38 million viewers per episode. “The Tonight Show Starring Jimmy Fallon” is averaging a 0.66 rating and 2.59 million viewers for the same time period.

At the conclusion of the standard September-May season, Colbert was averaging a 0.58 and 3.195 million viewers compared to Fallon’s 0.81 and 3.173 million. That means that Colbert has grown approximately 6% in total viewers while dropping approximately 9% in the key demo. Fallon, on the other hand, is down approximately 18% in total viewers and 19% in the key demo. While it is not uncommon for shows to experience a ratings drop off in the summertime, Colbert has made impressive gains.

Back in May, Colbert edged out Fallon in total viewers by just 0.69%. Now, Colbert enjoys a 27% lead over his NBC counterpart in that measure. Fallon is still the undisputed late-night king of the key demo, but his crown is not as secure as it once was. In May, Fallon outpaced Colbert by 33% in the key demo. Over the summer, that lead has slipped to 21%. Fallon is still handily in the lead, but the drop is nevertheless significant.

The two hosts have been going head-to-head in the ratings for months. Colbert’s viewership numbers have surged ever since the election of Donald Trump, with Colbert’s pointedly political comedy resonating strongly with viewers in Trump’s America. Earlier this week, Colbert’s interview with ousted White House Communications Director Anthony Scaramucci helped lift “The Late Show” to its highest-rated Monday telecast since Colbert took over the CBS late-night show.

Fallon, meanwhile, has largely stayed out of politics but has made some serious forays into political matters, such as on Monday this week when he made a statement on the violence in Charlottesville during his opening monologue. “The fact that it took the President two days to come out and clearly denounce racists and white supremacists is shameful,” Fallon said. “And I think he finally spoke out because people everywhere stood up and said something.”

“Jimmy Kimmel Live,” which airs on ABC in the same timeslot as Colbert and Fallon, has remained relatively stable over the summer. In the September-May ratings, Kimmel was averaging a 0.48 and 2.2 million viewers. For the summer, he is averaging a 0.47 and 2.03 million, meaning he has only dropped by approximately 2% in the key demo and 8% in total viewers.

In the 12:35 a.m. time slot, NBC’s “Late Night with Seth Meyers” is number one in both key measures for the summer, averaging a 0.35 and 1.35 million viewers per episode. ABC’s “Nightline” is second with a 0.3 and 1.3 million. CBS’ “Late Late Show with James Corden” is third with a 0.24 and 1.21 million.