I agree with what Mark Feld wrote. My paternal grandmother was actively buying coins in the late 1970's, and my recollection of prices she paid, even for generics like gem BU 1881S Morgan dollars, still makes my head spin. There was too much uninformed investor money in the coin market at that time. Buyers mostly did not have accurate perceptions of what was rare and what was common. The release of population data from TPGs and the rise of the internet was quite revealing, and caused me to dump my 20th century U.S. coins and turn to 18th-19th-century material. The internet in particular has changed the coin marketplace so much that I don't think that attempts to compare 2017 with 1980 or 1989-90 are useful.