The Greek Police publishes statistics on crime rates every year. In the Excel file there used to be a comparison with previous years. When there was a jump in crime rates, they stopped adding the comparison and no one bothered to do it themselves to report it in the media. The government will say that they still publish the same data, but in reality they make it more difficult to use them.
Making the data available may be important for researchers who may extrapolate trends and correlations, but it is as important to be doing these analyses for publishing the data in the first place.
Moreover, selecting which data to publish and which not should be as difficult as possible for governments, otherwise they would be able to only publish the ones that shows them in a favourable light.