although our revenues are principally derived from customers domiciled in the u.s. , the ultimate points of origination or destination for some products transported by us are outside the u.s . each of our commodity groups includes revenue from shipments to and from mexico . included in the above table are freight revenues from our mexico business which amounted to $ 2.2 billion in 2015 , $ 2.3 billion in 2014 , and $ 2.1 billion in 2013