, PubMed has more than 30 million citations and abstracts dating back to 1966, selectively to the year 1865, and very selectively to 1809. , 20 million of PubMed's records are listed with their abstracts, and 21.5 million records have links to full-text versions (of which 7.5 million articles are available, full-text for free). Over the last 10 years (ending 31 December 2019), an average of nearly 1 million new records were added each year. Approximately 12% of the records in PubMed correspond to cancer-related entries, which have grown from 6% in the 1950s to 16% in 2016.