In a sign of their declining popularity, late-night comedians Jimmy Kimmel, Stephen Colbert, and Jimmy Fallon have seen their ratings plummet for more than four months straight, as viewers in the coveted 18-49 year old demographic are tuning out consistently compared to last year, according to data reviewed by Breitbart News.

For last week, the three major late-night shows experienced a 19 percent drop from last year in their average weekly viewership in the 18-49 demographic. These declines tend to be between 10 percent and 20 percent every week as far back as mid July, though some weeks saw even bigger drops. The week ending October 10 saw a 28 percent drop from the same week last year.

The data showed similar but less precipitous drops for total households.

The across-the-board ratings decline signals trouble for the three major networks as they continue to use their late-night shows to push a radical left-wing agenda while demonizing conservatives.

CBS’ The Late Show host Stephen Colbert recently attacked the Supreme Court in anticipation of its abortion ruling that could overturn Roe v. Wade. ABC’s Jimmy Kimmel has used his show to prop up Dr. Anthony Fauci, recently smearing the government official’s critics as “scumbags” and “screwballs.”

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NBC’s Tonight Show attempted to bury online versions of last year’s gushing interview with then-New York Gov. Andrew Cuomo (D) and host Jimmy Fallon, after the governor resigned in disgrace in August.

NBC’s The Tonight Show Starring Jimmy Fallon appears to be trying to hide a gushing interview it conducted last year with disgraced New York Gov. Andrew Cuomo (D) by turning the YouTube video to “private” mode, which blocks the public from viewing the now-embarrassing video. (NBC)

CBS’ The Late Show with Stephen Colbert has reigned supreme for five consecutive seasons as the most-watched of the three major late-night shows. But the networks are now facing growing competition from Fox News’ Gutfeld!, which offers a right-leaning answer to mainstream late-night comedy.

On some weeks, Gutfeld!, which launched in April, has managed to draw more viewers than Kimmel, Colbert, or Fallon, although the Fox News show tends to skew toward older viewers.

Follow David Ng on Twitter @HeyItsDavidNg. Have a tip? Contact me at dng@breitbart.com