View Single Post
Old October 20, 2012, 06:13 PM   #3
johnbt
Senior Member
 
Join Date: December 6, 1999
Location: Richmond, Virginia USA
Posts: 6,004
According to a Layne Simpson article in 2009, about 2 to 2.5 billion.
johnbt is offline  
 
Page generated in 0.04234 seconds with 7 queries