Since 2004 there has been very little *meaningful* change. Productivity has fallen despite the smartphone. You might be wondering why this info on the smartphone all of a sudden? I’ve received a critical mass of research. I believe that it is telling us that the smartphone is a double edged sword and we need to respect that.
Planet Money explains our period of falling productivity: http://www.npr.org/sections/money/2017/05/19/529178937/episode-772-small-change
This article explains the psychology of the smartphone and how it has made us less intelligent and is responsible for poor social skills and the gullibility crisis: