Sometimes all it takes to lead is for everyone else to be going backwards.

And so, the growth in metro Atlanta’s inventory – that is, the number of homes for sale – is the best in the nation for the past 12 months, even though most experts have continued to complain that there is a shortage of homes on the market, according to a report to be issued today by Zillow.

And in fact, Atlanta inventory did tick down 3.5 percent from December.

But Atlanta is one of only four metros to have positive inventory growth from January of last year to January of this year, the Seattle-based real estate research and listing firm concludes in the study to be released this morning.

The number of homes for sale in metro Atlanta grew 6.8 percent over the year, Zillow says.

Only Houston, Pittsburgh and Washington, D.C. had any inventory growth at all.

Moreover, despite a price increase of 6.6 percent over the year, the region's affordability, which is often touted as one of Atlanta's most winning attributes, also continues, according to Zillow: Metro Atlanta's median price was the 25th highest in the country and was below the nation's median, too.

However, experts have been warning for several years that the price of housing has risen too fast for many lower-income people and young adults who are still renters to enter the market as buyers. And low inventory is a major factor pushing prices up: it is the class economic formula of low supply and high demand.

So higher inventory is considered crucial to a healthier, more inclusive market.

Inventory in January – even after the year’s modest improvement – was a stunning 51 percent lower than when the market was just starting to emerge from its downturn in early 2011.

Later today, the much-watched Case-Shiller report, which focuses on price of resales, is to be released.