Coming off its least-watched month in primetime in 20 years in May, CNN has taken another big ratings blow: The cable news network has registered to its lowest-rated quarter in primetime since 1991. For this year’s second quarter, CNN hit a low among total viewers and the key adults 25-54 demographic, with all primetime programs posting steep declines. The network averaged 446,000 total viewers and 129,000 in the 25-54 demo in primetime. Compared to last year’s second quarter, that’s down 35% and 41%, respectively. Rival Fox New Channel, meanwhile, with 1.79 million primetime total viewers on average, was down 1% from its 2011 second-quarter numbers. FNC lost 14% in the 25-54, bringing in 355,000 viewers. MSNBC was down 13% in total primetime viewers, with 689,000 on average, and down 17% in the 25-54 with 217,000. The quarter ran March 26-June 22.

Individually, CNN shows hemorrhaged viewers heavily compared with last year. Wolf Blitzer’s The Situation Room, which airs from 4-6 PM ET, was down 42% in 25-54 and 26% in total viewers. His show is expanding to three hours beginning Friday, taking over CNN’s recently cancelled John King U.S.A. At 7 PM, Erin Burnett OutFront, which debuted in October replacing a then-moving John King U.S.A., was down 45% in 25-54 from last year’s second quarter and down 33% in total viewers. Piers Morgan Tonight, which replaced Larry King Live in January 2011, was down 33% in the 25-54 and 29% in total viewers. Pulling double duty, Anderson Cooper took a double hit: Anderson Cooper 360 at 8 PM was down 23% in the 25-54 and 19% in total viewers, and its 10 PM airing was down 48% in the demo and 44% in viewers. The top-rated cable news shows for the second quarter were all FNC shows, with The O’Reilly Factor and Hannity sitting at No. 1 and No. 2.