German Frosted Glass Mother Goose Lamp Shade

I cherish this lampshade I received from an elderly friend of mine. I have had it since 1985, and I believe he brought it to America when he came to America from Germany in the early 1900's (he also left me his naturalization papers). The glass is smooth inside and frosted on the outside. The motif's are Mother Goose, the Muffin Man, Mary had a Little Lamb, Old King Cole, One of the Three Little Pigs, Little Jack Horner, The Pied Piper and Baa-Baa Black Sheep. Elephants and Bears are alternated between the motif's, and there are birds around the top and bunnies around the bottom of the shade. Over the 27 years I have had this shade, I have taken this to more antique shops than I can count, and no one could ever tell me anything about it. I'd love to hear if anyone knows the origin or history of this beautiful glass shade.