Breslov has no central membership roll, so the scholarly estimate of its committed core is a researcher's reading of community size rather than a dated census, and the sources reporting it do not state the year the underlying fieldwork or count was made.
What would resolve this A published methodology note from the estimate's original researcher, or a fresh dated count of registered Breslov institutions and their affiliated households, would anchor the figure to an actual year.
OpenGershon David Hundert (ed.), The YIVO Encyclopedia of Jews in Eastern Europe