Denis G. Pelli:
"Nearly everyone reads. Soon, nearly everyone will publish. Before 1455, books were handwritten, and it took a scribe a year to produce a Bible. Today, it takes only a minute to send a tweet or update a blog. Rates of authorship are increasing by historic orders of magnitude. Nearly universal authorship, like universal literacy before it, stands to reshape society by hastening the flow of information and making individuals more influential.
To quantify our changing reading and writing habits, we plotted the number of published authors per year, since 1400, for books and more recent social media (blogs, Facebook, and Twitter). This is the first published graph of the history of authorship. We found that the number of published authors per year increased nearly tenfold every century for six centuries. By 2000, there were 1 million book authors per year. One million authors is a lot, but they are only a tiny fraction, 0.01 percent, of the nearly 7 billion people on Earth. Since 1400, book authorship has grown nearly tenfold in each century. Currently, authorship, including books and new media, is growing nearly tenfold each year. That’s 100 times faster. Authors, once a select minority, will soon be a majority." (http://seedmagazine.com/content/article/a_writing_revolution/)