"Scooby-Doo" has maintained a significant fan base, which has grown steadily since the 1990s due to the show's popularity among both young children and nostalgic adults who grew up with the series. Several television critics have stated that the show's mix of the comedy-adventure and horror genres was the reason for its widespread success. As Fred Silverman and the Hanna-Barbera staff had planned when they first began producing the series, "Scooby-Doo"s ghosts, monsters and spooky locales tend more towards humor than horror, making them easily accessible to younger children. "Overall, ["Scooby-Doo" is] just not a show that is going to overstimulate kids' emotions and tensions," offered American Center for Children and Media executive director David Kleeman in a 2002 interview. "It creates just enough fun to make it fun without getting them worried or giving them nightmares.