Nickelodeon, launched in 1979, has been the number one children's TV network across all key kid demographics for 13 straight years, with over 72 million viewers each month. Nick owns 8 of the top 10 preschool shows with the other 2 being owned by Disney Channel. Their extensive book publishing program focuses on the network's preschool properties, the best of which (SpongeBob SquarePants, Dora the Explorer, Go Diego Go!) have each sold millions of titles to date.