of Pittsburgh within Allegheny County, with an average yearly household income of just over $218,000. Sewickely Heights is seen as one of Pittsburgh's wealthiest suburbs culturally as well, titles which the suburbs of Upper St. Clair, Fox Chapel, Wexford, and Warrendale also have been bestowed. In a 2002 study, Pittsburgh ranked 22nd of 69 urban places in the U.S. in the number of residents 25 years or older who had completed a bachelor's degree, at 31%. Pittsburgh ranked 15th of the 69 places in the number of residents 25 years or older who completed a high school degree, at 84.7%. The metro area has shown greater residential racial integration during the last 30 years. The 2010 census ranked 18 other U.S. metros as having greater black-white segregation, while 32 other U.S. metros rank higher for black-white isolation. As of 2018, much of Pittsburgh's population density was concentrated in the central, southern, and eastern areas. The city limits itself have a population density of 5,513 people per square mile; its most densely populated parts are North Oakland (at 21,200 per square mile) and Uptown Pittsburgh (at 19,869 per square mile). Outside of the city limits, Dormont and Mount Oliver are Pittsburgh's most densely-populated neighborhoods, with 11,167 and 9,902 people per square mile respectively. Economy Pittsburgh has adapted since the collapse of its century-long steel and electronics industries. The region has shifted to high technology, robotics, health care, nuclear engineering, tourism, biomedical technology, finance, education, and services. Annual payroll of the region's technology industries, when taken in aggregate, exceeded $10.8 billion in 2007, and in 2010 there were 1,600 technology companies. A National Bureau of Economic Research 2014 report named Pittsburgh the second-best U.S. city for intergenerational economic mobility or the American Dream. Reflecting the citywide shift from industry to technology, former factories have been renovated as modern office space. Google has research and technology offices in a refurbished 1918–1998 Nabisco factory, a complex known as Bakery Square. Some of the factory's original equipment, such as a large dough mixer, were left standing in homage to the site's industrial roots. Pittsburgh's transition from its industrial heritage has earned it praise as "the poster child for managing industrial transition". Other major cities in the northeast and mid-west have increasingly borrowed from Pittsburgh's model in order to renew their industries and economic base. The largest employer in the city is the University of Pittsburgh