Common Sense Media has compiled several studies about reading and their results show a decline in teens reading for pleasure over time. 

• About a third of 13-year-olds and almost half of 17-year olds reported that they read for pleasure less than twice a year.
• Reading scores have improved since the 1970s, except for older teens where 17-year-old measures remain about the same.
• Perhaps the most distressing finding is that the reading gaps between different races in the US have been unchanged in the last 20 years. 
• 46% of white children are proficient readers
• 20% of Hispanic children are proficient readers
• 18% of African-American children are proficient readers

You can read coverage of this report on several sites, though I can’t seem to find the full report online.

• Huffington Post
• NPR
• Time