Amazon (NASDAQ:AMZN) was responsible for 44% of all U.S. e-commerce sales and 4% of all retail sales in 2017, according to One Click Retail. The report also identified Amazon's four best-selling product categories of the year.

A chart of the four best-selling product categories on Amazon.

Data source: One Click Retail. Chart by author.

Home and kitchen product sales grew the fastest, rising 20% year over year, followed by 11% growth in sports and outdoors items. Consumer electronics sales rose 4%, while sales of published goods (mainly books) grew just 3%.

Amazon's strength in consumer electronics was likely aided by its own devices. In late December, the company claimed that its Echo Dot smart speaker was its best-selling product of the holiday season. 

One Click Retail also revealed the four-fastest growing product categories on Amazon: Luxury beauty, pantry, grocery, and furniture products grew 47%, 38%, 33%, and 33%, respectively.

Amazon is also expanding into these categories with its private-label brands, AmazonFresh grocery deliveries, and new furniture brands. As Amazon expands its reach, its brick-and-mortar rivals will need fresh ways to counter the e-commerce behemoth.

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