Nielsen released a new report today indicating that 40% of mobile users in the U.S. own smartphones and 40% of those are Android devices. That’s consumers over the age of 18.

iOS devices, the firm reports, are in second place with 28%.

“Among those who say they are likely to get a new smartphone in the next year, approximately one third say they want their next smartphone to be an iPhone and one third say they want an Android device,” says Don Kellogg, Director of Telecom Research and Insights at Nielsen. “However, among those who say they are usually the first to embrace new technologies, “Innovators” or the earliest of early adopters, Android leads as the “Next Desired Operating System” – 40 percent for Android compared to 32 percent for iOS. (Survey respondents were asked several questions to determine their attitudes toward new technologies.)”

“Among likely smartphone upgraders, it is the ‘Late Adopters’ who are most likely to say they are ‘not sure’ which operating system they’d like in their next smartphone,” says Kellogg. “In politics as in smartphones, these ‘undecideds’ will be the ones device makers will be hoping to win over.”

Google recently reported that over 150 million Android devices had been activated.