The chart shows five sets of column pairs. In each pair, one column represents the decade of 2001 to 2010 and the other 2011 to 2020. Each pair of columns shows the cause of the region's serious pipeline incidences. Within each column are bands of color which represent the number of serious incidences by OKI county. For the decade of 2001 to 2010, "Incorrect Operation" was the number one cause of serious pipeline incidences in the OKI region. This value dropped to zero in the past decade.