Because there is such a wide variety of holidays, you will have to create
your list of holidays. Once you have created the list (by date, not name),
you can use:
=COUNTIF(C2:C1800,">=7/10/03")-COUNTIF(C1:C18,">12/10/03")
to find the number of holidays in your list between July10, 2003 and
December 12, 2003.