blood crook who used the costume to cover up their crimes, the villain is arrested and taken to jail, often with the catchphrase "if it weren't for those pesky/meddling kids". Scheduled opposite another teenage mystery-solving show, ABC's The Hardy Boys, Scooby-Doo became a ratings success, with Nielsen ratings reporting that as many as 65% of Saturday-morning audiences were tuned in to CBS when Scooby-Doo was being broadcast. The show was renewed for a second season in 1970, for which eight episodes were produced. Seven of the second-season episodes featured chase sequences set to bubblegum pop songs recorded by Austin Roberts, who also re-recorded the theme song for this season. With Stefanianna Christopherson having married and retired from voice acting, Heather North assumed the role of Daphne, and she continued to voice the character until 1997. The TV influences of I Love a Mystery and Dobie Gillis were apparent in the first episode. Of the similarities between the Scooby-Doo teens and the Dobie Gillis teens, the similarities between Shaggy and Maynard are the most noticeable; both characters share the same beatnik-style goatee, similar hairstyles, and demeanors. The core premise of Scooby-Doo, Where Are You! was also similar to Enid Blyton's Famous Five books. Both series featured four youths with a dog, and the Famous Five stories often revolved around a mystery which invariably turned out not to be supernaturally based, but simply a ruse to disguise the villain's true intent. The role of each character was strongly defined in the series: Fred is the leader and the determined detective, Velma is the intelligent analyst, Daphne is danger-prone, Shaggy is a coward more motivated by hunger than any desire to solve mysteries, and Scooby is similar to Shaggy, save for a Bob Hope-inspired tendency towards temporary bravery. Later versions of the show made slight changes to the characters' established roles, such as showing the Daphne in 1990s and 2000s Scooby-Doo productions as knowing many forms of karate and having the ability to defend herself, and reducing her tendency towards being kidnapped. Scooby-Doo itself influenced many other Saturday-morning cartoons of the 1970s. During that decade, Hanna-Barbera and its rivals produced several animated programs also featuring teenage detectives solving mysteries with a pet or mascot of some sort, including Josie and the Pussycats (1970–71), The Funky Phantom (1971–72), The Amazing Chan and the Chan Clan (1972–73), Speed Buggy (1973–74), Goober and the Ghost Chasers