A prototype Rollkers transportation device is displayed during a press event at the Mandalay Bay Convention Center for the 2015 International CES on January 4, 2015 in Las Vegas, Nevada. The product is not a skate; it balances for you and when you place it on the bottom of your shoe, it gives you the ability for faster transportation based on walking. The balance CES, the world's largest annual consumer technology trade show, runs from January 6-9 and is expected to feature 3,600 exhibitors showing off their latest products and services to about 150,000 attendees. (Photo by Ethan Miller/Getty Images)

A girl dances in front of the digital art installation “Light in Dark” created by teamLab, a collaborative of Japanese digital artists, during a special exhibition of “Shake! Art Exhibition! and Learn and Play! teamLab Future Park” at National Museum of Emerging Science and Innovation (or Miraikan) in Tokyo, Japan, 19 January 2015. The exhibition is held through 01 March 2015. (Photo by Kimimasa Mayama/EPA)

News personality Katie Couric, left, Jenna Dewan-Tatum, center, and model Chrissy Teigen mingle during the White House Correspondents' Association dinner at the Washington Hilton on Saturday, April 25, 2015, in Washington. (Photo by Evan Vucci/AP Photo)

Revelers take a selfie during a Holi Festival in Madrid, Spain, Sunday, April 26, 2015. The festival is based on the Hindu spring festival Holi, also known as the festival of colours where participants colour each other with dry powder and coloured water. (Photo by Andres Kudacki/AP Photo)

A florist waits for customers at the Piedra Liza flower market in Lima April 29, 2015. The market sells flowers that come from all over Peru. Peru is home to more than 25,000 varieties of flowering plants like geraniums, carnations, roses, hydrangeas and jasmine, according to local media. (Photo by Mariana Bazo/Reuters)

A tea garden worker plucks tea leaves inside Aideobarie Tea Estate in Jorhat in Assam, India, April 21, 2015. Unrest is brewing among Assam's so-called Tea Tribes as changing weather patterns upset the economics of the industry. Scientists say climate change is to blame for uneven rainfall that is cutting yields and lifting costs for tea firms. (Photo by Ahmad Masood/Reuters)

James Spears takes his 1964 German built Amphicar for a drive on Lake Mead in Nevada May 6, 2015. Its a journey many drivers dream of, rather than travelling round a lake simply driving through it. But for James Spears it may be time to make the most of the waters in Lake Mead in Nevada, as water levels are plunging as California struggles to cope with a fourthsuccessive year of droughts. (Photo by Mike Blake/Reuters)

Framed by the setting sun, an American Bison grazes at the Tallgrass Prairie National Preserve on Tuesday, April 28, 2015, near Strong City, Kan. The buffalo herd at Tallgrass is one of the few herds of wild bison left in the United States. (Photo by Travis Heying/The Wichita Eagle via AP Photo)