New numbers out today from research firm Consumer Intelligence Research Partners (via AllthingsD) show that consumers in the U.S. are purchasing an increasing number of previous generation iPhones compared to recent years. It certainly helps make the case for a much rumored lower-cost iPhone, with the iPhone 4 capturing 18 percent of iPhones sold in the US during the June quarter, and the iPhone 4S an impressive 30 percent.

As noted by AllThingsD, the 52 percent of total iPhone sales captured by the iPhone 5 is much less than the iPhone 4S had just nine months into its release:

Nine months after the iPhone 5′s debut, it accounts for about half of all iPhone sales. The 4S still accounted for nearly three-quarters of iPhone sales almost a year after its launch.

While the obvious conclusion to draw from the data is an increased demand for a lower priced iPhone, CIRP’s Josh Lowitz thinks Apple could continue to take on the lower price market in the US with its previous generations of iPhones: expand full story