It might make sense for 1988 as this was for the bicentennial coins that were released for that year, which the commemorative 50 cents and dollar coin were struck. Perhaps the mint want to strike commemorative coins for the 20 cents piece but some were excessively struck and decision was to melt them down and strike new coins but they didn't make it somehow. Would be interesting if this is the case. I'm not too sure how the rest of the years are like but I'm still looking...
My partial coin collection http://www.omnicoin.com/collection/gxseries
My numismatics articles and collection: http://www.gxseries.com/numis/numis_index.htm
Regularly updated at least once a month.
My numismatics articles and collection: http://www.gxseries.com/numis/numis_index.htm
Regularly updated at least once a month.



















