Passage: Toshiba is headquartered in Minato-ku, Tokyo, Japan and has operations worldwide. It had around 141,256 employees as of 31 March 2018.Toshiba is organised into four main business groupings: the Digital Products Group, the Electronic Devices Group, the Home Appliances Group and the Social Infrastructure Group. In the year ended 31 March 2012, Toshiba had total revenues of ¥6,100.3 billion, of which 25.2 percent was generated by the Digital Products Group, 24.5 percent by the Electronic Devices Group, 8.7 percent by the Home Appliances Group, 36.6 percent by the Social Infrastructure Group and 5 percent by other activities. In the same year, 45 percent of Toshiba's sales were generated in Japan and 55 percent in the rest of the world.Toshiba has 39 R&D facilities worldwide, which employ around 4,180 people. Toshiba invested a total of ¥319.9 billion in R&D in the year ended 31 March 2012, equivalent to 5.2 percent of sales. Toshiba registered a total of 2,483 patents in the United States in 2011, the fifth-largest number of any company (after IBM, Samsung Electronics, Canon and Panasonic).

Question: How many patents did Toshiba register in 2011?
2,483