Finally, in the last window 2012–13, although there is no clear common trend for all groups it is evident that there is an upward tendency since, with the exception of group B, all other groups show a clear improvement in their average scale efficiency scores when going from year 2012 to 2013. The sixth section of Table 3 presents the number of scale efficient hospitals (CRS). As can be seen the maximum number of scale efficient hospitals is achieved (on average) in the two instances of year 2011 for all groups (with the slight exception of group A). Finally, as far as scale inefficiency is concerned, one should be able to distinguish whether it is attributed to increasing or decreasing returns to scale. The last section in Table 3 summarizes the detailed findings concerning the nature of scale returns for each hospital. The contents of this section show that, with the exception of group A, for which relevant findings are almost equally divided, there is a clear dominance of hospitals operating at increasing returns to scale (IRS).