via / more at wsj.com
Addendum:
The distribution of of usage on computers, smart phones and iPads over the day is based on the overall use of each device. So the curves does not mean that, for example at 21:00 clock twice as many users of online newspapers "enjoy" reading on their iPads, than reading on a computer device [e.g. 8 % of < 1 % is much less than 4 % out of 97 %].
