A new study conducted by the U.S. Centers for Disease Control and Prevention (CDC) revealed four in 10 households in the United States use only cellphones.

Stephen Blumberg, lead author of the study from the National Center for Health Statistics division of CDC, and his team have been studying phone use for more than a decade. They've observed the number of households using mobile phones is continuously increasing at an average of five percent per year.

"We switched to only cellphones three years ago. The only time we would get calls on the landline was from telemarketers," Justin Hodowanic, an 18-year-old college freshman from Atlanta, shared with the Associated Press.

The researchers interviewed at least 21,000 households by phone from June to December 2013.

Aside from the increasing number of households that rely on mobile phones for communication, the CDC survey also discovered three percent of the population did not have any phone - neither landline nor mobile. In 2009, about nine percent had landlines, while 48 percent had access to both landline and mobile phones at home. But by end of 2013, 17 percent of the households had landlines only, while 60 percent had both landlines and mobile phones.

In addition, younger people use mobile phones more often than older members of their families. About 75 percent of the respondents aged 20 and above live in households that have mobile phones only. Only 14 percent of the senior-aged respondents had cellphones.

The CDC survey also discovered that women favored landlines more than men. Not only that, the survey also revealed that the number of households with mobile phones only was the highest in the Midwest. In the Northeast region of the country, only 25 percent of the households have mobile phones only.

Blumberg speculated that most Americans wouldn't let go of their landlines because it was likely linked to their cable TV or Internet subscription.

Click here to read the full details of the CDC study.