Two stamps with maps were issued in Iraq in 2004 to celebrate
“Prevalence Day.” It is assumed by some that this is intended to be a
celebration of the return of civil authority to an interim Iraqi
government of 2004-6-30, the date on the low value of the set.
However, authority was returned two days earlier. On the other hand,
the phrase “prevalence day,” is frequently used to identify the day
when the prevalence of certain diseases is assessed.