Where are the 70 million?

End of August we reached a surprising high number of more than 70 million concurrent Skype users online!

The next graph represents the number of concurrent Skype users online on September 09, 2013.
The fluctuations are mainly due to day and night usage of the users in the different time zones. In 2008 I tried to explain the shape of the curve, see my post.

But, what surprised me is the following fact: Monday is usually the peak day in users online, but after the “false outlook induced growth” of end of August we had a quite significant downward trend (rounded numbers):
  • Monday, September 09: 62 million
  • Tuesday, September 17: 62 million
  • Monday, September 23: 58 million
  • Monday, September 30: 58 million
See the graph below, showing the downward trend in the two weeks starting on Saturday September 14, the lowest week points being the nights from Saturday to Sunday on 14/09, 21/09 and 28/09, the last one being less then 34 million:
Skype growth stopped? Or still adjustments due to the Outlook.com integration?