Details on the number of households qualified for social housing support in each local authority area are provided in the statutory Summary of Social Housing Assessments (SSHA), which has been carried out on an annual basis since 2016.
The most recent assessment, carried out in June 2018, which is available at the link below, shows that 71,858 households were assessed as qualified and being in need of social housing support. This represents a decrease of 13,941 households or 16.2% on the last assessment in June 2017. A breakdown of this figure by the length of time households have been on the list is also available at the following link, although it does not record data on a month by month basis in the manner sought.
http://https://www.housing.gov.ie/sites/default/files/publications/files/summary_of_social_housing_assessments_2018_-_key_findings.pdf