Gains at Amazon Fresh have proved to be more stable. The increases there also started well before the arrival of COVID-19 on U.S. shores. They were up over 100% from last year for January and February, before rising to 300% for April and May. That increase dipped slightly below 300% for the first part of June. 

At their April peak, Kroger's online sales expanded by roughly 125% beyond 2019's numbers. That figure has slowly dipped since then, but is still more than 100% above the previous year. 

Aggregate online sales hit a record $6.6 billion in May, according to a survey conducted by  Brick Meets Click and Mercatus. 

Even before the coronavirus emerged as as a force that would destabilize the U.S. economy, the online grocery sector was poised for a strong 2020. Researchers at global measurement company Nielsen said at the end of 2019 that online sales had grown an average of 45% for each of the past three years. 

But much of that growth had been concentrated in a small pocket of buyers. Ten percent of shoppers accounted for half of these new sales. 

The pandemic has certainly helped broaden the base of users. In May, according to the Brick Meets Click and Mercauts survey, 43 million individuals had shopped online for groceries over the past thirty days. In August 2019, that figure was just 13.1 million. 

"COVID-19 has accelerated online grocery adoption at a rate the industry hadn't expected to see for years," Mercatus CEO and president Sylvain Perrier said in a statement. "The online surge may level off slightly as various states strive to return to 'normal.' However, what has changed in shoppers' eyes is the realization of the immediate benefits of online grocery shopping."