“American Idol” would love these ratings. NBC’s “The Voice” scored a whopping 4.9 Monday night in the key age demo. The singing contest also pulled in a total of 13.67 million viewers. The show was so hot that it beat the NCAA Basketball pre-game show and took its time period easily. “The Voice” has broken out as a show that attracts a young audience compared to “American Idol”–now sort of like “Lawrence Welk” with key demo numbers around 2.8. An even older skewing show is last night’s “Dancing with the Stars,” which rated a 2.0 in the key demo even though it pulled in 12.94 million viewers. That means that most of the people watching “Dancing with the Stars” may have had trouble getting up and walking to the kitchen for a snack unaccompanied by an aide.