My 1st response after reading this is: 50 million  a year, at 15 years adds up to 750 million(50x15=750), not 1.5 billion. Take away the 300 million ghost bushels and that leaves 450 million carryover. That amounts to 30 million over 15 years(30x15+450). My second response is: who and how does someone come up with trend yields? In the last ten years, 5 were over 150(one of those barely) and 5 were under 150(three well under). How is that figured?