Figure 2

The current number of existing (a) tree graphs and (b) dual graphs in each graph vertex number (from 2 to 10 for tree graphs and from 2 to 9 for dual graphs) in the updated RAG database. Each bar is divided by the topological classifications that were constructed in 2004 (existing, RNA-like, and non-RNA-like) which are represented as red, blue and green, respectively. Since the launch of RAG in 2004, more than twice as many topologies have been identified, most of which have been confirmed from RNA-like topologies (see the second column of Tables 1 and 2 for the distribution of existing motifs in each vertex number from 2 to 10 for tree graphs and from 2 to 9 for dual graphs, respectively).