OK they have covered why there were so many dollars. The reason for the low mintages for the rest of the coins is the same reason the mintage of the 2009 coins went down so much. The country was in the middle of a recession. There is typically a recession at the end of a war, in this case WWI, because of the high unemployment from all the soldiers coming home and the layoffs from all the industries that had been geared up for war production. In a recession coins came back out of hoards and those coins in circulation stayed there and didn't have to be replaced. This meant much less demand for new coins and low mintages.