From a Nielsen Blog Post:
According to Nielsen’s fourth-quarter 2015 Comparable Metrics Report, smartphones across all adult demographic groups are the most used platform, in terms of days per week among users of each medium—with adults 18+ using their devices nearly every day in the week (5.8 times per week), followed by television (5.5 times per week). Adult TV viewers watch an average of 5.5 days per week.
Tablets are used more often by people ages 35-49 than ages 18-34. Penetration among ages 50 and over is only 19%, but those owners use tablets most often.
Smartphone owners within the age range of 35-49 use their phones most often. (This includes app and web usage, not talk, text or email).
Read the Complete Blog Post
Additional Data/Chart From Nielsen: The Comparable Metrics Report: Q4 2015