Ratings for AMC's hit show "The Walking Dead" have taken yet another plunge, but the show remained on top in ratings Sunday night. The third episode of the eighth season, titled "Monsters," saw more than 8.5 million viewers on Sunday night, with a 3.8 rating in the key demographic. Last week's episode took in more than 8.9 million viewers and had a 4.0 rating.The premiere of the eighth season saw 11.4 million viewers. "The Walking Dead" airs Sunday nights on AMC.