Pairwise distance distribution for the genomic-length sequences of HBV genotypes A, B, C, D, E, F, H and I. Probability densities of pairwise distances for whole-genome sequences of HBV genotypes. Genotypes E, F, H and I are shown on a separate plot from genotypes A–D as they contained smaller number of sequences. Too few sequences were available after filtering for genotypes G and (putative) genotype J to be analysed.