Polar bear Knut was born in captivity at the zoo on 5 December 2006. He and his twin brother or sister were directly rejected by their mother on the day of birth. He was subsequently raised by zookeeper Thomas Dörflein and became the center of a mass media phenomenon that spanned the globe, quickly spawning numerous toys, media specials, DVDs, and books. Because of this, the cub was largely responsible for a significant increase in revenue, estimated at about five million euros, at the Berlin Zoo in 2007. Zoo attendance figures for the year increased by an estimated 30%, making it the most profitable year in its 165-year history. Knut died on 19 March 2011 after collapsing in his exhibit.