Sometimes the most important data is the hardest to come by. In this case, I'm referring to historic sales figures from homebuilder KB Home (KBH -0.80%), the nation's fifth largest builder by units sold. As I've noted previously, while this is arguably the single most accurate reflection of a homebuilder's performance, not to mention the overall housing market, a comprehensive data set containing the data is nowhere to be found.

Source: Quarterly and annual filings

It's for this reason I decided to collect the information and share it in the chart below -- to see similar figures for D.R. Horton, PulteGroup, Lennar, and NVR, click here, here, here, and here, respectively. While researching the health of the broader economy, I dug through the quarterly filings of the largest homebuilders. My purpose was to gauge how well the market for new homes had recovered. While the market had struggled to date, the chart above, along with Lennar's stellar earnings earlier this week, show that things are on the mend.

There are two reasons investors should care about this. First, if you own shares of KB Homes, it goes without saying that the more homes it sells, the higher its stock will climb. And second, because KB Homes is a dominant player in the housing market, its success and/or failure is somewhat indicative of both that industry and the economy more generally. As my colleague Morgan Housel has previously observed, "there hasn't been a strong economy without a strong housing market in modern history."