During Q3 last year, 22% of Bay Area households could afford an entry-level home; in S.F. county alone it was 17%. This year's Q3 numbers (unchanged from Q2), came in at 18% and 15%, thus 4% and 2% fewer could afford an area property. This is despite overall CA existing home median prices dropping by 9.9% in the past year. Prices down, affordability down too? Is it the still-solid high-end S.F. real estate that's bending the Bay numbers a little? Or something more insidious?