The NYTimes has the numbers that show this election season has been particularly good for the cable news channels…

in the first half of 2008 and the cable networks showed two dozen candidate debates, CNN had, on average, 32 percent more 25- to 54-year-old viewers than during the same period in 2004, while MSNBC (starting from a much smaller base) averaged 73 percent more. The Fox News Channel showed a 17 percent decline compared with the same time period, but still had more viewers than the other news channels.

…while not being much help at all to the three broadcast evening newscasts…

the traditional standard-bearers of television news — have been unable to stop their long-term ratings declines, even during the hotly contested primaries. The newscasts on NBC, ABC and CBS had an average combined audience of 23.7 million viewers from January to June, down 2 percent from the same time period in 2007.

Phil Griffin, president of MSNBC, tells the Times this is a trend that he expects will keep viewers tuning in after Election Day. “More and more, the news game is being played out on cable.”