The TreeFam  ontology contains data about the evolutionary history (both orthologs and paralogs) of gene families. A gene family is defined as "a group of genes that evolved after the speciation of single-metazoan animals". Our ontology contains genes for individual species (human or mouse), thus families consist of paralogs.
Statistics can now be found in the footers of each table in the GREAT web output.
All data for human and mouse was downloaded and built between Oct 14, 2011 and Feb 18, 2012.
For zebrafish, data was downloaded Jan 3, 2011.
GREAT v1.8 TreeFam statistics are available here.
GREAT v1.2 TreeFam statistics are available here.
Ruan, J., et al. TreeFam: 2008 Update, Nucleic Acids Res. 2008 Jan; 36(Database issue):D735-40.