of children under age 5 living in Manhattan has grown by more than 32%. In 2000, about 3 out of every 10 New York City housing units were owner-occupied, compared to about 2 owner-occupied units out of every 3 units in the U.S. as a whole. Rental vacancy is usually between 3% and 4.5%, well below the 5% threshold defined to be a housing emergency, justifying the continuation of rent control and rent stabilization. About 33% of rental units fall under rent stabilization, according to which increases are adjudicated periodically by city agencies. Rent control covers only a very small number of rental units. Some critics point to New York City's strict zoning and other regulations as partial causes for the housing shortage, but during the city's decline in population from the 1960s through the 1980s, a large number of apartment buildings suffered suspected arson fires or were abandoned by their owners. Once the population trend was reversed, with rising prospects for rentals and sales, new construction has resumed, but generally for purchasers in higher income brackets. Profile and comparison Comparison with other cities New York is the largest city in the United States, with the city proper's population more than double the next largest city, Los Angeles (or roughly equivalent to the combined populations of Los Angeles, Chicago, and Houston, the United States' second, third, and fourth most populous cities respectively). In 2006, demographers estimated New York's population would reach 9.1 million by 2030. In 2000 the reported life expectancy of New Yorkers was above the national average. Life expectancy for females born in 2009 in New York City is 80.2 years and for males is 74.5 years. Profile New York's two key demographic features are its density and diversity. The city has an extremely high population density of 26,403 people per square mile (10,194/km2), about 10,000 more people per square mile than the next densest large American city, San Francisco. Manhattan's population density is 66,940 people per square mile (25,846/km2). The city has a long tradition of attracting international immigration and Americans seeking careers in certain sectors. As of 2006, New York City has ranked number one for seven consecutive years as the city most U.S. residents would most like to live in or near. Immigration Throughout its history New York City has been a principal entry point for immigration to the United States. These immigrants often form