By 2022, consumers shopping online with merchants outside their home country will account for 20% of all online spending, according to a forecast on cross-border e-commerce from Forrester Research Inc. Further, 40% of online shoppers around the world will make cross-border purchases regularly.

The money spent across borders will reach $627 billion in 2022, Forrester analyst Michael O’Grady projects, noting that Chinese shoppers are at the root of the increased activity. (The projection includes online spending for ticketing and travel, in addition to retail goods.) Today, half of cross-border e-commerce spending comes from China.

Cross-border is also a substantial part of e-commerce in the Middle East and North Africa (MENA) region, where 50% of money spent online goes to merchants outside the consumer’s home country. Amazon.com Inc., seeking a foothold in the region, closed on its $580 million acquisition of Dubai-based Souq.com earlier this week. Today, cross-border sales account for almost 25% of marketplace units sold on Amazon, the report says.

“The ‘buy globally and sell globally’ paradigm of cross-border commerce will see significant change over the next five years, driven by e-commerce growth in Asia and the emergence of new e-commerce markets in Africa and the Middle East,” O’Grady writes in his June report.

The majority of cross-border purchases, 66%, are taking place on online marketplaces, such as Amazon, eBay Inc., and AliExpress, a global marketplace operated by China’s Alibaba Group Holdings. 91% of U.K. consumers surveyed say they make cross-border buys on a marketplace, as do 88% of German online shoppers, 84% of Italian shoppers, 77% of French shoppers and 72% of Spanish shoppers.

U.S. consumers are less likely to shop at websites in other countries. According to Forrester figures, 52.9 million U.S. consumers will be cross-border buyers this year. That number is expected to reach 68.6 million in 2022. There were 321.4 million people in the United States as of 2015, per census estimates. Using that number means 16.4% of U.S. consumers will be a cross-border buyer this year. That would increase to 21.3% in 2022 if the U.S. population does not increase.

Measured across all markets, apparel and consumer electronics are the top two types of products consumers buy when shopping across borders.