(RECAP: Mortgage rates are still below 4.5%, rates that were unheard of before 2011. And home values, while up at least 11% over the last two years, are still well below their bubble-era peak. The NARs’ housing affordability index shows that housing is still more affordable than anytime between the early 1990s and 2008. What’s not to like? The problem is that this picture of affordability assumes borrowers have down payments of at least 20% and that they’re able to qualify for the lowest mortgage rates. A new analysis from Goldman Sachs shows that for marginal borrowers, including many first-time buyers, the picture of affordability is only so-so.)