Every year Heather Morrison reports on the past year with figures on her blog The Imaginary Journal of Poetic Economics. For her, 2018 was the “best year yet for net growth of open access”. Here are some figures on journals, articles and books which are indexed in the main repositories and archives.

Directory of Open Access Journals (DOAJ) indexes over 12,000 journals with more than 3.6 million articles from 9479 journals available for access just as articles. Over 1700 journals were added in 2018 including 1600 which give access to individual articles. This represents a growth of 16%.
Bielefeld Academic Search Engine (BASE) indexes nearly 140 million documents with around 84 in open access. This represents a growth of 16%.
Directory of Open Access Repositories (OpenDOAR) indexes 3799 open archives [a growth of 10%], Registry of Open Access Repositories (ROAR) 4735 [a growth of 3%].
Directory of Open Access Books (DOAB) has 13,253 books from 285 publishers with nearly 3000 additions. This represents a growth of 28%.
Registry of Open Access Repository Mandates and Policies (ROARMAP) has made a survey of 960 policies in favour of open access including 71 in 2018. This represents a growth of 8%.
PubMed Central (PMC) went past the barrier of 5 million articles in 2018 [a growth of 13%]. Over 1500 journals offer all their articles in open access from a total of over 7000 journals.
The open archive arXiv possesses around 1.5 million preprints which is an increase of 140,000 in 2018. This represents a growth of 10%.

The complete data can be downloaded from the blog’s database at: https://hdl.handle.net/10864/10660.

Extra data can be given for France which comes from the barometer of open science . The level of open access is 36% for 2017.