The University of Pennsylvania, Temple University, Drexel University, and Thomas Jefferson University comprise the city's nationally ranked research universities. One of the founding members of the Association of American Universities is in the city, the University of Pennsylvania, an Ivy League institution with claims to being the oldest university in the country. Philadelphia has emerged as a hub for information technology and biotechnology. For comparison, on an inflation-adjusted basis, the median household income among metropolitan areas was $60,482, down 8.2 percent in the same period, and the national median household income was $55,250, down 7.0 percent from 2008. The murder count dropped in 2002 to 288, then rose to 406 by 2006, before dropping slightly to 392 in 2007. , As of December 31, 2016, there were 1,102,620 registered voters in Philadelphia.  Twentieth-century black newcomers were part of the Great Migration out of the rural south to northern and midwestern industrial cities. One of the most prominent mainline Protestant jurisdictions is the Episcopal Diocese of Pennsylvania. In 1876, Philadelphia hosted one of the country's first international expositions, to commemorate the centennial of the Declaration of Independence. Entrance and exit ramps for the Benjamin Franklin Bridge are near the eastern end of the expressway, just west of the I-95 interchange. A library was founded in Philadelphia in 1731 and a theater was built in 1766. The Library Company of Philadelphia founded.  All three representatives are Democrats though Republicans still have some support in the city, primarily in the Northeast. Less than 1% of Philadelphia's Christians were Mormons.  On July 13, 1985, John F. Kennedy Stadium was the American venue for the Live Aid concert. Each frame had gradually increased the powers of the elected assembly and it now received more privileges than any other legislative body in the English colonies, undoubtedly more than Penn, himself, had originally intended. Philadelphia has some notable modern buildings. , The Puerto Rican population in Philadelphia is the second-largest after New York City, and the second-fastest growing after Orlando. Penn’s influence and participation in the Quaker-inspired West Jersey Proprietorship were important factors in his approach to governance in Pennsylvania, including religious guarantees, freeholder representation and respect for Native Americans. Of Philadelphia's adults, 31 percent were married or lived as a couple, 55 percent were not married, 11 percent were divorced or separated, and 3 percent were widowed.  Philadelphia contains 67 National Historic Landmarks and the World Heritage Site of Independence Hall. History of Philadelphia, Pennsylvania. Philadelphia gave much to the War for Independence. , Philadelphia's 30th Street Station is a major railroad station on Amtrak's Northeast Corridor with 4.4 million passengers in 2017 making it the third-busiest station in the country after New York City's Pennsylvania Station and Washington's Union Station.