When did "actresses" become "actors"?

[JoeM]

[quote deckeda]...You'd refer to a single female as actress, and a group of females as actresses, but a group of actors and actresses as actors.
Females on most talk shows I see have been referring to themselves as actors for quite some time now so I would think your statement isn't correct in the industry anymore yet I can't seem to recall ever reading or hearing anything about when and why the change in reference occured.