Fundamental changes are rare and arise only in extraordinary historical situations.
In order to assess the likelihood that a new voting system might be adopted it is useful to understand the circumstances under which organizations are typically motivated to change their voting systems. However, smaller changes have occurred at the national level and changes of all types have occurred below the national level and in non-governmental organizations. Many countries have made minor changes to their voting systems. In recent years the Greek voting system has undergone the most changes, with five different voting systems in use in Greece between 1974 and 1990. Major change occurs most often at times of great social and political change.