To find the average rate of change, you subtract the farm count in 1982 from the count in 2012, then divide by the difference in years. So, (2,110,000 - 2,480,000) / (2012 - 1982) = -370,000 / 30 = -12,333.33 farms per year. This means the number of farms decreased by an average of about 12,333 each year from 1982 to 2012.