In markets big and small, retail e-commerce is maintaining its impressive growth.

The 2015 Global Retail E-Commerce Index highlights the big and the small: the countries that are always going to be e-commerce behemoths because of their size, and the smaller yet still-promising markets where potential matters more than size.

This dichotomy plays out in the results of this year’s Index: The world’s largest markets for e-commerce dominate the top half of the top 30, led by the United States, China, and the United Kingdom (see figure 1). In the bottom half are some smaller markets, such as Mexico, whose potential for growth is impossible to ignore.