"B2B e-commerce [in the US] has now more than doubled B2C, with $559 billion in 2013 sales" http://www.forbes.com/sites/brianwalker/2014/05/06/why-e-commerce-still-isnt-clicking-with-b2b-executives/ …
See also the source Forrester report: http://blogs.forrester.com/andy_hoar/12-10-18-us_b2b_ecommerce_sales_to_reach_559_billion_by_the_end_of_2013 … That trend is a beautiful example of "the internet" being done right.