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And Instagram in 2011...

Notice on the graph that the drop pretty much starts around 2012. Quite interesting, and it definitely probably needs to be investigated more. They also mention the correlation between lower scores and higher leisure phone use.

Android 4.0 Ice Cream Sandwich https://en.wikipedia.org/wiki/Android_version_history

On 4.0 Android become mature enough to dominate market and to become world wide.

First usable version was around 1.6..2.2, around 2009..2010 after them begin mass production and 4.0 become world wide phenomenon.

Even, considering, Android copied many traits of iPhone, but iPhone was that time limited joy of rich and geeks. With Android 4 everybody enter smartphone era.

These apps weren't widespread immediately, so it took a while to spread and the effect is a lagging measure as well.

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