Yum! Brands Inc. plans to double Taco Bell’s domestic annual sales to $14 billion by 2021, per analysts who attended investor meetings with the company. Louisville, Ky.-based Yum, which also operates and franchises KFC and Pizza Hut, told attendees that system growth would include an increase in average unit volumes from $1.3 million in fiscal 2012 to about $1.8 million by the end of the decade. The plan is also to grow unit count from 5,700 to 8,000 locations.