Answer: If you could add the graph to your question so I can see what it looks like, that would be great! I would probably be able to answer it, then. :)
From the given table, it can be seen, that the amount of milk that Winconsin diary farms produced in 1972 is 7 billion pounds and that the amount of milk that Winconsin diary farms produced in 1997 is 8 billion pounds.
