Sesame Street is a long-running American children's television series created by Joan Ganz Cooney and Lloyd Morrisett. The program is known for its educational content, and images communicated through the use of Jim Henson's Muppets, animation, short films, humor, and cultural references. The series premiered on November 10, 1969 to positive reviews, some controversy, and high ratings. The show has undergone significant changes throughout its history. The format of Sesame Street consists of a combination of commercial television production elements and techniques which have evolved to reflect the changes in American culture and the audience's viewing habits. With the creation of Sesame Street, producers and writers of a children's television show used, for the first time, educational goals and a curriculum to shape its content. It was also the first time a show's educational effects on young children were studied. Shortly after creating Sesame Street, its producers developed what came to be called "the CTW model" (named for the show's production company, The Children's Television Workshop), a system of television show planning, production, and evaluation based on collaborations between producers, writers, educators, and researchers. The show was initially funded by government and private foundations but has become somewhat self-supporting due to revenues from licensing arrangements, international sales, and other media. By 2006, there were independently produced versions, or "co-productions", of Sesame Street broadcast in twenty countries. In 2001 there were over 120 million viewers of various international versions of Sesame Street, and by the show's 40th anniversary in 2009, it was broadcast in more than 140 countries. By its 40th anniversary in 2009, Sesame Street was the fifteenth-highest rated children's television show in the United States. A 1996 survey found that 95% of all American preschoolers had watched the show by the time they were three years old. In 2008, it was estimated that 77 million Americans had watched the series as children. As of 2009, Sesame Street has won 8 Grammy Awards and 153 Emmy Awards—more than any other children's show.