China has taken the top spot as the country with the most online retail ROI potential, according to the management consulting firm A.T. Kearney’s annual ranking of the top 30 countries in online retail.

This year’s A.T. Kearney Global Retail E-Commerce Index includes a combination of 30 developed and developing markets with China occupying the top position, and the G8 countries–Japan, the U.S., the U.K., Germany, France, Canada, Russia, and Italy–all within the top 15.

A.T. Kearney looked at 186 countries to determine the ranking of the top 30 countries, evaluating each on four dimensions and nine variables and then ranking the retail e-commerce growth opportunity for each country. The higher the ranking, the more near-term ROI potential a country has in online retail.

With e-commerce being increasingly viewed by retailers as an efficient and effective global expansion vehicle, many developing countries made their way onto the ranking this year. E-commerce allows less developed markets to shortcut the traditional online retail maturity curve as online retail grows at the same time as physical retail becomes more organized.

The also list includes 10 “small gems,” as A.T. Kearney calls them–countries with populations of less than 10 million that have active online consumers and sufficient infrastructure to support online retail, including Singapore, Hong Kong, Slovakia, New Zealand, Finland, United Arab Emirates, Norway, Ireland, Denmark and Switzerland. Because of the investment profile required for global retailers or pure-play e-tailers, these small gems can be powerful online retail markets.

Globally over the past five years, online retail has grown at a 17 percent compound annual growth rate, with growth particularly strong in Latin America (27 percent) and Asia Pacific (25 percent).

Additionally, the study found that mobile is becoming a critical e-commerce enabler. Ninety-three percent of mobile phone owners in Brazil and 51 percent in the U.K. use their devices to learn about retail offerings.

Social media is also having a major impact, but in different ways. Developing markets such as China encourage shoppers to write post-purchase reviews in exchange for loyalty points or online coupons. In developed markets, online retailers such as Amazon mine purchase reviews for insights on products, instruction manuals and supply chain hiccups.

The study found that there are three very distinct kinds of retail e-commerce markets: