Books are like portals to different worlds. They can plunge readers into new, imaginative and informative places. But a new survey on American reading habits reveals a statistic that's all too real: 27 percent of U.S. adults didn't read a single book within the last 12 months.

The survey, which was conducted by Pew Research, asked adults if they had read a book in any format. The number of people who answered "yes" has fallen in recent years, from 79 percent in 2011 to 72 percent in 2015.

The news comes on the heels of mixed information about the book publishing industry. While print seems to be enjoying a resurgence, ebook sales are waning. That’s reflected in the survey data, too: 63 percent of respondents said they read a print book during the last 12 months, but ebook readership flattened during the same period.

Though the survey reports that the average American adult read 12 books in the last year — a number that seems to be skewed high by book lovers, as the median is only 4 — it's unclear how these reading habits affect literacy rates. The U.S. Census no longer measures literacy, and it's been more than a decade since the National Assessment of Adult Literacy reported that 11 million Americans lack basic literacy.

Still, there's hope for the book industry. According to the survey, 80 percent of young adults between the ages of 18 and 29 read a book during the last year. The future might belong to avid readers, after all.