Investing.com - Amazon (NASDAQ:AMZN) has become a "preferred shopping destination" and will account for almost 10 of all retail sales by 2020, according to one Wall Street firm.Telsey Advisory Group issued that prediction, along with an outperform rating and a $1,900 stock price target in a note to clients.Telsey said Amazon will continue to grow at an "amazing" rate because of its "customer-centric approach", operational efficiency, technology platforms and Prime membership plan.Amazon just increased its Prime annual fee by $20, a move that will generate $2 billion in additional annual revenue.Telsey said Amazon's best multi-year growth opportunities are in the food and drug markets. Several other Wall Street firms recently raised their forecasts on Amazon after it reported blockbuster first-quarter earnings. Amazon shares are already up 35 this year.