Prior to the acquisition of the full genome sequence, estimates of the number of human genes ranged from 50,000 to 140,000 (with occasional vagueness about whether these estimates included non-protein coding genes). As genome sequence quality and the methods for identifying protein-coding genes improved, the count of recognized protein-coding genes dropped to 19,000-20,000. However, a fuller understanding of the role played by sequences that do not encode proteins, but instead express regulatory RNA, has raised the total number of genes to at least 46,831, plus another 2300 micro-RNA genes. By 2012, functional DNA elements that encode neither RNA nor proteins have been noted. and another 10% equivalent of human genome was found in a recent (2018) population survey. Protein-coding sequences account for only a very small fraction of the genome (approximately 1.5%), and the rest is associated with non-coding RNA genes, regulatory DNA sequences, LINEs, SINEs, introns, and sequences for which as yet no function has been determined.