As of September, 2012 - the amount outstanding and in circulation is currently $239 MILLION in United States notes.
See mid way down on page 11 in the link provided below:
http://www.treasurydirect.gov/govt/r...opdm092012.pdf
Between the $239 Million currently outstanding and remaining in circulation + the $25 MILLION they think may have been lost or destroyed ($264 MILLION), there would only be $39 MILLON left that could be currently issued in United States currency notes to reach the $300 MILLION Dollar limit.
F.y.i.