plants, 5.2% by natural gas, and 0.4% by oil. The company traded its common stock on the New York Stock Exchange, and in 1976, the company issued a preferred stock (formerly ) with a 10.5% dividend, callable in 1990. APS also performed well through the early 1980s recession, reaching peak earnings of over US$255 million in 1983. However, by then the company had accumulated over US$2.1 billion in long-term debt. In 1982, APS issued another preferred stock (formerly ) with an 11.9% dividend, callable in 1987. And in 1983, it issued a third preferred stock (formerly ) paying an adjustable rate between 6 and 12%, through 1986. 1984 was a down year for both earnings and the stock price, which at its low that year had lost almost half its value from the 1983 peak. Service territory APS serves about two-thirds of the Phoenix metropolitan area. It primarily serves downtown and northern Phoenix, as well as a large swath to the north and east of the city. Outside of the Valley, it serves Flagstaff, Prescott, Yuma and Douglas. Major power outage On September 8, 2011, there was a widespread power outage affecting a region spreading west from Yuma, Arizona, to San Diego, California, and affecting parts of Northern Mexico. The outage was the result of 23 events that occurred on five power grids in a span of 11 minutes including the APS North Gila Substation. Federal, regional and local officials are investigating what happened and why the outage cascaded the way it did. Most of the areas affected were served by San Diego Gas & Electric, which saw its entire service area lose power. The outage appears to have been caused by the actions of an APS employee in the North Gila substation, and it is unknown why safeguards did not keep the outage limited to the Yuma area. The outage occurred days before the tenth anniversary of the September 11 attacks, and hours before the United States Department of Homeland Security warned of a potential terrorist attack leading up to the anniversary, but the Federal Bureau of Investigation and SDG&E early in their investigations ruled out terrorism. Blackout settlement On July 7, 2014, APS agreed to a $3.25 million settlement with NERC and FERC related to the September 2011 blackout. 2018 Street Protests On September 7, 2018, APS cut off the power to 72-year-old retiree Stephanie Pullman, due to