between 1998 and 2009
Between 1998 and 2009, the total number of hog operations fell by about 60 percent, and the average inventory grew from 2,589 to 7,930 head. Over this period, the number of hog operations producing fewer than 300 animal units declined rapidly, resulting in a shift in production to larger operation. In 2009, over half of all hog production occurred in operations with 1,000 or more animal units.
[pdf source usda]