Lemma list derived from the representative synchronic written corpora of the SYN series. The format is quite straightforward, it is a simple tsv file with the columns in the following order: lemma POS SYN2000 SYN2005 SYN2010 SYN2015

where every corpus is in fact represented by two columns, with frequency and i.p.m., so the total number of columns in the file is 10. The lemma list is filtered and includes only alphabetical lemmas with non-zero frequency in all four corpora.