Reed Hastings, chief executive officer of Netflix, speaks during a news conference in Tokyo on Monday, June 27, 2016.

Despite Netflix's huge rally this year, a Wall Street firm says the stock will go even higher based on an analysis of Google search data.

Piper Jaffray told its clients on Monday that the video streaming company could have as much as 42 percent year-over-year gains in its international subscriber base in the third quarter, in line with the consensus estimate. Analyst Michael Olson also predicted that domestic subscriptions will increase 10.9 percent from the third quarter last year, which is higher than the 10.7 percent consensus estimate.

Netflix had 51.9 million domestic members as of the end of June and 52 million international members.

Olson reiterated his overweight rating on the stock and his price target of $215, which is 18 percent higher than Netflix's Friday closing price.

But the analyst said the analysis of Netflix search trends on Google points to potential domestic growth of 16.2 percent and international growth of 78.3 percent. While the analyst noted that the Google search model is likely "overstating" subscription growth potential, "it is clearly positive from a directional perspective."

Piper Jaffray's search analysis had a 96 percent correlation with Amazon's retail sales unit growth in the previous 20 quarters.

"We believe Netflix is well positioned to have over 100 million international subscribers by 2020, along with ongoing operating margin expansion as the company spreads content and marketing spend over a growing installed base," Olson wrote.

Netflix is one of the market's best-performing stocks, rallying 47.3 percent this year through Friday compared with the S&P 500's 11.7 percent gain.

The analyst detailed several ways Netflix could reach 164 million subscribers worldwide by 2020 — and that excludes business in China.

"Our 2020 year-end subscriber estimate of 164 million worldwide assumes 64 percent domestic and 19 percent international share of broadband subscribers (excludes China from addressable base)," Olson said. "While this level of penetration (domestically) is higher than most comparative subscription entertainment products, we believe the content/value ratio offered by Netflix is, and will continue to be, higher than other relevant comparative offerings."

Last quarter, Netflix crushed Wall Street's estimates, adding 5.2 million total members versus expectations of 3.23 million. Netflix is set to report third-quarter earnings mid-October.