Does any one have a good idea how much helium america has left in it's reserves?

Question

1) I've read about LTR ( lighter than air ) recently.
and apparently helium is a very limited resource.
2) When we run out, thats it, no more helium.
3) America has always had most of the worlds supply,
lucky us, since being used to our advantage in WW1 and WW2.

Answer 1

The National Helium Reserve is an American strategic reserve of over a billion cubic feet of Helium gas, stored at the Cliffside Storage Facility about 12 miles northwest of Amarillo, Texas in a natural geologic gas storage formation. It was established in 1925 as a supply of lifting gas for airships, and in the 1950s became an important source of coolant during the Space Race and Cold War.

Answer 2

Helium is the most abundant natural gas ,
See occurrence & production about 2/3 of the way down

http://en.wikipedia.org/wiki/Helium