Adults without landlines are more likely to be smokers and heavy drinkers

New results released by the Centers for Disease Control reveal that two of every five American households have ditched their landlines for cellphones -- and there are interesting differences between the health of households that still have landlines and those that are wireless-only.

The data are part of a preliminary study from the National Health Interview Survey, a part of the CDC's statistics department that regularly conducts tens of thousands of phone and in-person interviews to get a snapshot of Americans' health.

In 2003, the agency decided to also look at how many households have landlines to better tailor its survey. Since then, it's become the most prominent government agency collecting the data. Overall, 39.1 percent of adults are in wireless-only households; that number goes up to 47.1 percent when the figure also includes children.

You may expect that young adults are primarily driving the trend toward households that only use cellphones -- something that has certainly been true in the past. But 2014 marked the first time that, by a slim majority, adults 35 and older make up the largest portion of households that rely solely on cellphones. In line with other studies looking at the demographics of technology use, Hispanic adults are also far more likely to be living in households that only had wireless phones.