The year 2021 won't be marked down as a great one for Amazon (AMZN -0.29%) shareholders. The stock's on pace to log a very un-Amazon-like full-year gain of around 4%, dramatically trailing what will end up being about a 27% romp for the S&P 500 (^GSPC 0.55%). Like so many other companies, the e-commerce giant also got bit by the inflation bug, at least in investors' eyes.

The coming year, however, is very likely to be very different. Three easy-to-understand charts illustrate why Amazon shares could -- and should -- rekindle their long-standing rally.

1. Amazon Web Services is on fire

You may know the company as an e-commerce outfit. The fact of the matter is, though, Amazon makes far more money by selling cloud computing services than it does by selling merchandise.

The graphic below puts things in perspective. Over the course of the past four reported quarters, Amazon Web Services (AWS) has produced operating profits of nearly $17 billion, vs. retail sales operating income of around $11.5 billion. Granted, rising fulfillment, shipping, and payroll costs took an unusually big toll on the third quarter's bottom line. Even stripping out the unexpected impact of those soaring costs, though, AWS has been the bigger moneymaker since 2019.

Amazon Web Services is Amazon's biggest moneymaker, by far.

Data source: Amazon Inc. Chart by author. All figures are in millions of dollars.

Now extrapolate these growth trends. Assuming each of these three operating units maintains its current bigger-picture fiscal directory, AWS is on pace to generate around $21 billion worth of operating income in 2022, vs. e-commerce operating profits on the order of $14 billion. The company's cloud computing arm is poised to lead Amazon to not just record-breaking income but record-shattering income.

2. Gas prices should fall

Amazon's e-commerce earnings rebound will only take shape if rising freight costs pull back. The prices of gasoline and diesel soared early in the year and have continued to drift higher since then. Accordingly, Amazon noted 57%, 30%, and 20% increases, respectively, in worldwide shipping costs for its first, second, and third fiscal quarters of 2021. Fulfillment costs and cost of sales -- which also include delivery elements -- jumped similarly. Since diesel and automobile fuel prices have only pulled back a bit since reaching a multi-year high in November, there's not much reason to think Amazon will feel much relief on this front in the coming year.

Two people reviewing a printed chart at a desk.

Image source: Getty Images.

In its most recent update on the matter, however, the U.S. Energy Information Administration (EIA) forecasts the price of gasoline will slide lower to an average of $2.88 per gallon in 2022 and end the coming year at a price of $2.61 per gallon. For perspective, auto fuel is currently selling at $3.27 per gallon, on average.

Gasoline prices are projected to ease back from 2021's multi-year highs in 2022.

Data source: U.S. Energy Information Administration. Chart by author.

The outlook may seem more like wishful thinking than a realistic assessment of the situation, but it actually makes sense when you consider how long it can take the oil drilling and exploring industry to plan and execute new projects. As the EIA's forecast notes, "For 2022 as a whole, we expect that growth in production from OPEC+, of U.S. tight oil, and from other non-OPEC countries will outpace slowing growth in global oil consumption, especially in light of renewed concerns about COVID-19 variants."

3. E-commerce is still the minority of retailing

Finally, perhaps the most compelling reason to expect continued growth from Amazon in 2022 is the visualization of how much retail business the company isn't doing.

Yes, the e-commerce platform is a giant, to be sure. Market research outfit eMarketer estimates Amazon controls 40% of the U.S. online shopping market alone. That leaves the other 60% up for grabs if Amazon can find a way to win it. What's not always entirely appreciated, however, is that Amazon has room to grow its top and bottom lines even if it never adds to its current market share. For as big as Amazon and its online shopping peers collectively are, e-commerce still only accounts for about 15% of the country's total retail spending, a proportion more or less mirrored in overseas markets.

E-commerce sill only accounts for a small fraction of the United States' (and the world's) total retail spending.

Data source: U.S. Census Bureau and Federal Reserve. Chart by author. Dollar figures are in millions.

To be clear, the chart above only considers retail dollars that Amazon has a legitimate chance at winning. The total retail sales figure excludes cars, auto parts, and gasoline sales.

To put the visualization in a more numerical perspective, last quarter's countrywide e-commerce spending of $214 billion is still $1.1 trillion less than the total amount Americans spent on goods like clothes, electronics, furniture, hardware, food, and cleaning supplies. In other words, there's still lots of room for growth.