Especially my study investigates the changes during the past few years. The preliminary results indicate that the collaborative and international authorship has increased. The share of a single author is about 40% in my data.
Guha, Shion, et al. "Following bibliometric footprints: the ACM digital library and the evolution of computer science." Proceedings of the 13th ACM/IEEE-CS joint conference on Digital libraries. ACM, 2013.
Bartneck, Christoph, and Jun Hu. "Scientometric analysis of the CHI proceedings." Proceedings of the SIGCHI Conference on Human Factors in Computing Systems. ACM, 2009.
When youre are more interestes in science in general: in the Netherlands, the Rathenau Institute does a lot of work. Check for example the profile of Edwin Horlings.