This is all I could find in the brief time I have this morning:
“By the time the battle for the Ryukyu Islands ended American forces had expended 97,800 tons of ammunition, most of that tonnage in artillery. Indeed taking into account the size of the invading force, the length of the fighting front, and the duration of the campaign, the invading force’s concentration of naval, air, and ground fire unmatched in the history of warfare.”
http://www.history.army.mil/brochures/ryukyus/ryukyus.htm
More than two Iowa class battleships.
It's interesting that in the Philippine valleys where there are no mountains or jungles the Japanese defense is far less effective.
The pictures of the happy homecomings are really great to see!