From The Muppet Wiki:
"Statler and Waldorf
rate the show like Olympic judges. First, they give Kermit
a 2. Then, they give the opening a 3, but the audience demands they bring it down to a zero. All of the Muppets get low scores (though Fozzie
's "1" is a compliment by them), and Gonzo
even gets a -6. The Muppets think it's just a tough audience, but Diana
gets 10's every time which gives her high scores."