Between the shrimp cocktail shooters and flashy performances at their upfront presentations, you would have no idea that traditional TV networks have a very real problem on their hands.

The big picture: According to four years of data from Nielsen's Total Audience Reports, every age group except those aged 65+ is spending less time — and in the case of younger Americans, far less time — watching television live or via DVR.

Go deeper: How American TV consumption is changing, in one chart.