New York City has focused on reducing its environmental impact and carbon footprint. Mass transit use in New York City is the highest in the United States. Also, by 2010, the city had 3,715 hybrid taxis
and many pedestrian commuters make it the most energy-efficient major city in the United States.[444] Walk and bicycle modes of travel account for 21% of all modes for trips in the city; nationally the rate for metro regions is about 8%.[445] In 2011, Walk Score named New York the most walkable city in the United States.[446][447] Citibank sponsored the introduction of 10,000 public bicycles for the city's bike-share project in the summer of 2013.[448] Research conducted by Quinnipiac University showed that a majority of New Yorkers support the initiative.[449] New York City's numerical "in-season cycling indicator" of bicycling in the city hit an all-time high in 2013.[450]