Prior to 2000, only seven film series had grossed over $1 billion at the box office: "James Bond", "Star Wars", "Indiana Jones", "Rocky", "Batman", "Jurassic Park", and "Star Trek". Since the turn of the century that number has increased to over fifty (not including one-off hits such as "Avatar", "Titanic", and "Zootopia"). This is partly due to inflation and market growth, but also to Hollywood's adoption of the franchise model: films that have built-in brand recognition, such as being based on a well-known literary source or an established character. The methodology is based on the concept that films associated with things audiences are already familiar with can be more effectively marketed to them, and as such are known as "pre-sold" films within the industry.