The keynote slides of Mary Shaw at the The 7th joint meeting of the European Software Engineering Conference (ESEC)
and the ACM SIGSOFT Symposium on the Foundations of Software Engineering (FSE) August 24-28 2009 Amsterdam, The Netherlands are available at: Keynote
Referencing their seminal work on end-user programming:
C. Scaffidi, M. Shaw, and B. Myers. Estimating the Numbers of End Users and End User Programmers.VL/HCC’05: Proc 2005 IEEE Symposium on Visual Languages and Human-Centric Computing, pp. 207-214, 2005.
Mary shaw gives some figures on the number of end-user programmers: