Some librarians are “savers”. Others are “tossers”. These terms refer to an individual’s propensity for keeping books (and now, electronic sources). In the dim, dark past (say, up to about the mid 1960’s) most libraries had to beg for materials and wouldn’t DREAM of getting rid of things no matter how out-of-date the information was, because then there wouldn’t be any books on the shelves. But in the early 1960’s as the Russians outdid us in the space race and governments began generously funding libraries practically everywhere, libraries filled their shelves up, and librarians were happy. They MIGHT have even gotten rid of a few things they didn’t need. This lasted until the mid-1980’s sometime. Funding dwindled as taxpayers expressed frustration and politicians made “no new taxes” promises.
The funding looked like this, in a totally unscientific graph of my own devising: