For example, if you want to see what retired in 2010, select the year 2010, select "ended", then "List pieces". You'll get a list of pieces no longer available in 2010. This list will contain pieces officially retired by the Factory as well as limited pieces, specials, and anything else that was not officially retired but because unavailable on the primary market for one reason or another.
If all you want is a list of pieces officially retired in a particular year, you may get that information from the Factory Web site. What you get from the Factory should be a subset of what you get from the Master List, although there can be some minor differences in earlier pieces.