Costco NASDAQ: COST has been a big winner so far this year. Consumer staples stocks have generally had a good year, with the Consumer Staples Select Sector SPDR Fund NYSEARCA: XLP providing a total return of 15%. However, that still lags the over 20% return of the S&P 500.Costco has particularly impressed. Its 33% total return this year surpasses its sector and the industry by a wide margin. So, what has been driving Costco’s recent success, and is there still room for this stock to run?Get Costco Wholesale ...