As far as efficiency trend is concerned, the finding that emerged from window analysis is the following. Although the results do not reveal the existence of a clear and consistent inter-temporal trend in any of the four groups there is, however, an indication that year 2011 constitutes a turning point in the whole 5-year period since the upward efficiency trends for all groups in window 2010–11 are turning downwards in window 2011–12. A similar finding is documented in another study  according to which the middle-sized hospitals (100–400 beds) of the Greek NHS exhibit efficiency improvement in the period 2009–2011.