Almost two-thirds -- 64 percent -- of adults in the US now own a smartphone, according to a new report from Pew Research Center. That's up from 58 percent in early 2014. Back in 2011 Pew reported that just 35 percent of American adults were smartphone owners. Pew's recent report is based on a number of surveys, including a telephone survey of more than 2,000 people conducted last December and a web and mail survey of more than 3,000 people conducted in October 2014.

Pew's new survey data confirms that smartphone ownership is still higher among younger adults, those with higher income and education levels. Some 85 percent of 18- to 29-year-olds own the devices. About 78 percent of all college graduates do, and 84 percent of adults living in households with an annual income of $75,000 or more per year own them too. Interestingly, 27 percent of people 65 and up now own a smartphone, up from 19 percent in early 2014. 

This year's survey also explored smartphone dependence -- the extent to which people relied on the devices for internet access. Pew found that 10 percent of adults in the US own a smartphone but don't have any other high-speed internet access at home. Beyond home-based internet access, the survey also found that 15 percent of adults own a smartphone but have a limited number of other options for going online. The overlap between these two groups is about 7 percent of US adults -- that group is smartphone-dependent for internet access, according to Pew's data.

Of all the uses Pew asked respondents in its survey, looking up health information about a particular condition was the most common thing smartphone owners did with their devices in the past year. About 62 percent of smartphone owners said they had used their devices for this purpose in the past year. That eked up to 63 percent for smartphone owners who are part of a household that earns less than $30,000 a year and ratchets down to 59 percent for smartphone owners in households that make $75,000 or more a year. It shoots up to 77 percent of adults aged 18- to 29-years-old. Some 68 percent of smartphone owners aged 30 to 49 used their phones to look up health information in the past year, while 39 percent of those aged 50 and older did.

Pew's whole report on smartphone adoption and usage in 2015 is available for free right here.