Photo Muppets question

I wasn't sure where to post this, I'm not refering too the replicas but the actual photo Muppets that were used for promo pictures of The Muppets and Sesame Street. When did The Jim Henson Company start making photo Muppets?

http://www.henson.com/jimsredbook/wp-content/uploads/2012/06/SS_877_6thSeasonCastPhoto.jpg
I found this on Jim's Red Book and I noticed that most of the Sesame Muppets are the actual puppets because you can see either stands or tripods below them.

So when did they start making specialized photo Muppets for pictures and stuff?

Good question and I would be interested to find out, too.I know they were used for "Muppet Magazine" which was the start of 1983,but then they also had full length Muppets for the high noon shot in The Muppet Movie, which was 1979.I dont think they had them in 1976, because for the Post card picture, which Sigma also used, they were main puppets.So I would say late seventies?Can anyone vary that or give a more pinpoint year?

I can't remember offhand the original source of the quote but i remember reading about how it was after they had done the first Miss Piggy calendar that they realized that creating photo Muppets would be a good idea.

So the first Miss Piggy Calendar was 1980, which would bring it back to 1979 when it was made.