Share of homes affordable to programmers in San Francisco, CA 2018

Teachers here include elementary, middle and secondary school teachers and the median income is calculated by taking the average of these sub-categories. Restaurant workers include cooks, food preparation workers, bartenders, and waiters and waitresses. First responders include police and sheriff’s patrol officers and firefighters. Doctors here are family and general practitioners. Programmers include computer programmers, software developers (applications), software developers (systems software) and web developers.
The source adds the following information: "affordability is defined as spending 31% or less of one’s monthly income on housing. In order to find the share of affordable homes on the market for the median income earner for each occupation we calculate the maximum amount that each person can allocate towards a mortgage payment based on their wage. We evaluated the listing price of each home effective March 29. We subtracted a 20% down payment and calculated the monthly mortgage payment using the prevailing 30-year mortgage rate (4.44%) at that time. We also considered HOA fees, mortgage insurance and property taxes. Finally, we took the number of listed properties that the median income earner for each occupation could afford."