In 2013 the number of people in the world who has visited websites with mobile devices is equalized to the number of people who has used for this purpose personal computers and laptops.
It is projected that by the middle of 2013 the number of visits to websites through tablets and smartphones will surpass the number of visits with personal computers and laptops.
Thus websites which are viewed equally well both on PCs and on mobile devices have an advantage over those which do not have such feature.
Hence we can conclude that those websites which are convenient to use on mobile devices will get 40-50% more customers.