The Central Statistics Office (CSO) and Northern Ireland Statistics and Research Agency (NISRA) have made available the series of Annual Reports on Marriages, Births and Deaths in Ireland from 1864 to 2000 inclusive.
They are full of detail about our ancestors social, educational, wealth, health and religious lives across the period, and I find them a not always comfortable mix of fascinating, surprising and shocking information about the times our ancestors lived through.
These reports have been scanned and converted into PDFs and can be freely downloaded here.
Annual reports for the years 2001 to 2011 are already available in the Births, Deaths and Marriages Archive on the CSO website.