You may notice it has been a while since one of these threads. From what I could tell, After reaching 12 million, Overwatch happened and numbers dropped by about 2 million. Took around half a year for the numbers to pop back (I assume a combo of growth and returning users).
For contrast:
5.01 Million concurrent users were reached on the 2nd January 2012
6.04 Million concurrent users were reached on the 25th November 2012
7.19 Million concurrent users were reached on the 1st December 2013
7.67 Million concurrent users were reached on the 29th December 2013
8.02 Million concurrent users were reached on the 29th June 2014
8.50 Million concurrent users were reached on the 2nd January 2015
9.06 Million concurrent users were reached on the 15th March 2015
10 Million concurrent users were reached on the 14th June 2015
11.1 Million concurrent users were reached on the 31st October 2015
12.2 Million concurrent users were reached on the 3rd January 2016
Also here's a look some of the peak stats:
DDOS if old
For contrast:
5.01 Million concurrent users were reached on the 2nd January 2012
6.04 Million concurrent users were reached on the 25th November 2012
7.19 Million concurrent users were reached on the 1st December 2013
7.67 Million concurrent users were reached on the 29th December 2013
8.02 Million concurrent users were reached on the 29th June 2014
8.50 Million concurrent users were reached on the 2nd January 2015
9.06 Million concurrent users were reached on the 15th March 2015
10 Million concurrent users were reached on the 14th June 2015
11.1 Million concurrent users were reached on the 31st October 2015
12.2 Million concurrent users were reached on the 3rd January 2016
Also here's a look some of the peak stats:
DDOS if old