In general, the mutation rate in unicellular eukaryotes and bacteria is roughly 0.003 mutations per genome per generation.[4] The highest per base pair per generation mutation rates are found in viruses, which can have either RNA or DNA genomes. DNA viruses have mutation rates between 10−6 to 10−8 mutations per base per generation, and RNA viruses have mutation rates between 10−3 to 10−5 per base per generation.[4] Human mitochondrial DNA has been estimated to have mutation rates of ~3× or ~2.7×10−5 per base per 20 year generation (depending on the method of estimation);[5] these rates are considered to be significantly higher than rates of human genomic mutation at ~2.5×10−8 per base per generation.[6] Using data available from whole genome sequencing, the human genome mutation rate is similarly estimated to be ~1.1×10−8 per site per generation.[7]