The graph represents the differences in regional unemployment rate per Member State expressed as the coefficient of variation of regional unemployment rates. As Eurostat states, ’the coefficient of variation is defined as the ratio of the standard deviation to the mean. This coefficient of variation is multiplied by 100 to make a percentage’.
This number is zero if the regional unemployment rates of a given Member State are equal. Significant differences between regional unemployment rates give a fairly high index. The index is not applicable to nine Member States because they have fewer than three NUTS 2 regions: Croatia, Cyprus, Estonia, Ireland, Latvia, Lithuania, Luxembourg, Malta and Slovenia.
From the graph it can be noted that five Member States show an increase in the index between 2004 and 2014, while 13 show a decrease, meaning that differences among regions got smaller.