Earth Hour 2011 was the biggest year in the campaign's five-year history, reaffirming it as the largest ever voluntary action for the environment. In 2011, the tagline "Beyond the Hour" was adopted by organizers as a way to encourage people to take their commitment to the cause beyond the 60-minute event. Together with agency Leo Burnett, Earth Hour unveiled an updated planet themed logo that included a small plus symbol to the right of the signature "60" which was used in previous years. The 60+ symbol continues to be the main logo used by campaign organizers around the world.