The Peace dollar was first struck in 1921 with an experimental high-relief engraving, which proved to be difficult to execute. This first 1922-S issue introduced modified-relief engravings which became the standard for the series. Most of the 17.5 million struck entered commerce, which translates to less than 1% remaining in mint-state condition today. Because of this, added collecting pressure is placed on Extra Fine specimens such as these.