Just wondering how many remember these folders?

Came across a couple dozen of them for 1960 and a half a dozen from 1964 and 1965 as they were originally released from the UNPA.
"As originally released" is often a good thing--but not in this case. Apparently, the UNPA's way of thinking in that generation provided the folder, and a glassine envelope containing the stamps of the year, but attached the glassine envelope to the folder with a piece of scotch tape!
Fast forward to 2010 and that scotch tape has lost its adhesion, had yellowed through years of storage, and has put an ugly scotch tape stain on the inside of each of the folders where the glassine had been affixed.
Just goes to show that it's not only collectors who do damage to their collections with the use of tape, but the postal administration's do it, too.