Jay Leno Jay Leno

The ratings for NBC's Tonight Show this summer have been nothing to laugh about.

As part of a downward trend across all of late-night TV, The Tonight Show with Jay Leno has hit a record low among the desirable adults-18-to-49 demographic, according to The Hollywood Reporter.

Since the end of the standing broadcast season in May, Leno is averaging 3.8 million viewers a night. Even though that's a 12 percent boost in viewers from Conan O'Brien's Tonight a year ago, it's down 23 percent in the demo.

Leno is, however, beating The Late Show with David Letterman by 22 percent in both measures. Overall, The Late Show is steady with its performance from the previous year, when it hit its own record low.

Also steady in the demo are The Late Late Show with Craig Ferguson, Late Night with Jimmy Fallon and Jimmy Kimmel Live!, while the latter two have shown gains in viewership from last summer.