Revisions to the data are published each month, together with the release of monthly data on births, deaths etc, and are explained in each issue of the bulletin. There is no advance notice of major changes in methodology. Explanatory notes are included in each news release. Monthly data are published about seven weeks after the end of the reference month. The bulletin publishes monthly and annual data.
Annual data are more detailed than monthly data.
Annual and monthly data refer to the most recent four years or most recent twenty months, respectively.