10/22 Deluxe Sporter

Does anyone know what year Ruger first offered the deluxe sporter (not the 1966 finger groove sporter)? Looks like the one below except with a plastic butt plate.

I had one that was built in 1972.

nevermind, I found the answer

They were introduced in 1971 with serial # 110-90067, plastic butt plate was switch to rubber in 1987