The answer is TV and, increasingly, the Internet.
Why doesn't the Internet count as "reading"?
Most of the time I spend on the net I spend reading forums like this or reading technical articles.
The only difference between that and reading a book is that I read more authors per unit of time.
Though I spend about as much time reading now as I did before the Internet, my attention span dropped significantly. There are so many disparate sources of information and distractions on the Internet, that I rarely read whole articles any more.
The real question here is - what do people prioritize above reading? And maybe a side question is, where do they get that sense of prioritization from?