key grafs<p>Because we have not allowed our population to grow commensurately with our post-1970 boom, we have forced price to do the work of balancing demand and supply. Instead of building all the houses and apartments we need, the existing houses and apartments have become more expensive.<p>As of 2015, the median annual household income in San Francisco was $90,530, and the average market-rate apartment rent is approximately $3,600 per month, or $43,200 per year. By these estimates, the average market-rate apartment rent consumes about 48 percent of the median household’s annual pre-tax income. This is a staggeringly high rate: A more normal level is for housing to cost between 25 and 30 percent of pre-tax income. No wonder San Francisco has the lowest housing affordability in the nation, and almost one quarter of the population living below the poverty level when local housing costs are factored in. The figures differ by county but are similar throughout the Bay Area.