Millennials will make 60% of their purchases online this year, up from 47% in 2017, according to a new CouponFollow study. The percentage of shopping done in brick-and-mortar stores is expected to decline from 53% in 2017 to 40% in 2019.

Amazon (AMZN -1.14%) will naturally benefit from that shift. Nearly two-thirds of millennials make at least 50% of their online purchases on Amazon, and only 3% don't use it at all.

Chart showing millennial usage of Amazon for online shopping.

Data source: CouponFollow. Chart by author.

That's why it isn't surprising that eMarketer expects Amazon to account for 47% of all U.S. e-commerce sales this year. The second- to fifth-largest e-tailers behind the tech titan could control a combined share of just over 16%.

It also indicates that Amazon's expansion of its Prime ecosystem, which CIRP estimates hit 101 million U.S. members at the end of 2018, will lock in more shoppers with free shipping options, discounts, and digital perks. CIRP believes that the average Prime shopper spends about $1,400 annually, compared to $600 for non-Prime shoppers.

Amazon dominates the online shopping space, but resilient retailers like Walmart and Target are still growing their digital sales at high-double-digit rates. Nonetheless, Amazon's strength among millennials could still crush the weaker players.

Check out the latest earnings call transcript for Amazon.