I finally completed a project that extended from 1999-2009. From random change I searched each quarter seeking one that was needed to complete the collection. Five quarters were issued each year with the first ones representing the states that first entered the union first. With the final shiny coin joining the flock in 1999.
The last holdout that took me over a year to find was Arizona.
The book has some weight to it and it feels like one is holding something of substance in your hand.
Since the pace of releasing the coins was over a long period it brings to mind the passage time, measured row by row.