With electric-car company Tesla's (NASDAQ:TSLA) stock price sharply rising to new highs almost every week recently, it's more evident than ever that the stock is priced for sustained growth for years to come. But why are investors so confident in Tesla's ability to grow?

There are a handful of reasons investors are betting Tesla can rapidly grow its vehicle sales in the years ahead, including the approximately 400,000 deposit-backed reservations the company has already garnered for its upcoming Model 3 and Tesla's leadership position in the fast-growing long-range EV segment. But one reason investors may be bullish on Tesla's future prospects is because of the company's staggering sales growth in the past.

Tesla Model X with a rear license plate reading, "Zero Emissions."

Tesla Model X. Image source: Author.

Here's a look at Tesla's incredible growth in three charts.

Annual deliveries are soaring

Thanks to the success of Tesla's Model S sedan and a follow-up launch of its well-received Model X SUV, Tesla's vehicle deliveries have risen sharply since 2012. Between the first half of 2012 and today, Tesla has gone from selling hundreds of vehicles a quarter to tens of thousands every quarter.

A bar chart showing Tesla's annual vehicle deliveries since 2012.

Data source: Quarterly SEC filings. Chart by author.

In 2016, Tesla delivered just over 76,000 vehicles, up 51% compared to its deliveries in 2015.

Model X proves Tesla isn't a one-hit wonder

Ahead of Tesla's launch of its Model X SUV in late 2015, there was no certainty the new vehicle would resonate with customers as well as the Model S did. After all, the Model S' success was alarming -- the vehicle's North American sales quickly rose to surpass those of all comparably priced luxury sedans, and Model S has continued to outsell similarly priced competition, whether it be electric, hybrid, or gas, ever since. But the Model X has similarly seen its sales soar, and sales don't look like they're done increasing yet.

Bar chart showing Tesla's Model X deliveries since Q3 2015.

Data source: Quarterly SEC filings. Chart by author.

Consider Tesla's Model X sales in its most recent quarter, which were up nearly 400% year over year and 21% sequentially.

Size is helping Tesla's growth accelerate

On the surface, it would seem reasonable to argue that Tesla's past growth is irrelevant to the big growth investors are expecting in the future. This past growth has been on a much smaller base, critics might point out. But Tesla's growth is accelerating as the company gets bigger.

A line graph showing Tesla's trailing-12-month vehicle sales growth rates.

Data source: Quarterly SEC filings. Chart by author.

For much of 2014 and 2015, Tesla's annual vehicle sales growth was under 50%. But Tesla is growing sales at higher rates recently.

Further, Tesla has kicked off 2017 with more extraordinary growth. Vehicle deliveries in the first quarter of 2017 were up 69% compared to the year-ago quarter, and for the first six months of 2017, Tesla expects deliveries to be up 61% to 71%, compared with the same period in 2016.

Tesla management is as confident as ever in Tesla's ability to accelerate its growth even more. For its July slated Model 3, Tesla is aiming to achieve a production rate of 5,000 vehicles per week by the end of the year, and 10,000 per week at some point next year.

Investors shouldn't automatically conclude that Tesla's uncanny growth will persist just because the company has consistently delivered strong growth in the past. What Tesla expects to do next is mind-boggling. Management is forecasting annual production will increase from a rate of about 100,000 units today to 500,000 next year. Still, these charts help provide some context behind the market's confidence in Tesla's ability to grow at huge rates in the future.

Daniel Sparks owns shares of Tesla. The Motley Fool owns shares of and recommends Tesla. The Motley Fool has a disclosure policy.