Nearly half of San Francisco's existing housing stock was built before 1940, and building since then has struggled to keep up with population growth. A new report from Paragon Real Estate examines the amount of residential building that has occurred per decade since 1940 and compares it to San Francisco's population growth over the same period of time. The low amounts of new housing built were less of a problem in the 1960s, 70s, and 80s, when the population of the city was falling. But once the 90s hit, population growth took off. The number of people living in San Francisco is currently at its highest level ever, at approximately 850,000. That's a 45,000-person increase since just 2010, with only 7,500 new housing units built in the same time.