The following sources are cited in SAP Digital Futures Issue 20: Let’s Talk About Conversational Computing

The first chatbot, ELIZA, was created in 1966.
Joseph Weizenbaum, “ELIZA—A Computer Program for the Study of Natural Language Communication Between Man and Machine,” Communications of the ACM, January 1966, http://dl.acm.org/citation.cfm?id=365168&dl=ACM&coll=DL.

As of 2015, people were spending more time on messaging apps than social networks.
“Messaging Apps Are Now Bigger Than Social Networks,” Business Insider Intelligence, September 20, 2016, http://www.businessinsider.com/the-messaging-app-report-2015-11.

2.19 billion people will use mobile messaging apps by 2019.
Number of Mobile Phone Messaging App Users Worldwide from 2014 to 2019 (in Billions),” Statista, retrieved December 20,, 2016, https://www.statista.com/statistics/483255/number-of-mobile-messaging-users-worldwide/.

Voice recognition technology is now about 95% accurate.
Kevin J. Ryan, “Who’s Smartest: Alexa, Siri, and or Google Now?” Inc., June 3, 2016, http://www.inc.com/kevin-j-ryan/internet-trends-7-most-accurate-word-recognition-platforms.html. 

20% of companies already use digital personal assistants.
Based on the results of a survey of over 1,000 IT and business professionals sponsored by SAP and conducted by IDC.