I suppose it's possible that different areas and years saw circulation, and that the fad of keeping them wore off and they got spent for a while. My accumulation from circulation was approx. 1974-1977, and then in early 1983 I was completely broke and spent my substantial stack of non-silver Kennedy's on cigarettes (so those circulated again). My late mother-in-law worked for the US embassy in Bangkok and gave me her stack of Kennedy halves she had obtained from circulation in Thailand - range of dates 1964-1976 or early 1980s maybe. Back on topic - it's really pathetic that the US mint has turned this into yet another manufactured "rarity." Everyone in this country should be getting these 250th designs in their change.