Really? What was the literacy rate in 1600, 1700, 1800 and 1900? Depending on what you define as "literacy," of course, will determine how literate the nation was. If you make say "able to sign your name" then your numbers will be higher. If you say "read and write prose, your numbers willbe lower. No wonder literacy rates were sampled according to the former standard, which is meaningless.
Just because you can sign your name doesn't mean you can read complex prose. So, to put this in perspective, according to one source, one hundred years after Gutenberg's invention, that is by the end of the 16th century, allegedly 50% of the population in England could sign their name!
On the other hand, the same source says that a century later in France as many as 75% of the population were illiterate (i.e. could not sign their name)! Accordingly, the government of France in 1880 published a report showing that between "1686 and 1690 the female literacy rate (based on ability to sign) was just 14 percent, while the male rate was 36 percent."
Allegedly Protestant Europe fared better than Catholic Europe, with literacy rates between 35 and 45 percent, that is literacy as in "sign your name." By 1861, four hundred years after Gutenberg, the 1861 Newcastle Report in England reported 67% "literacy" among men and 51% among women. Other sources say that by 1860, 40% of people in England could not sign their names.
Even if they could doesn't mean they could read and comprehend the Bible—or even afford one!? You made a claim which is not supported by facts. It seems that, in Protestant England, which was supposedly well ahead of Catholic France, the literacy rate—meaning one could sign his or her name (but not necessarily read)—grew from 50% to mere 67% among men and barely 1% among women over a 400-year time span!).
So, where are you getting your ideas from? And btw, I don't use Google. Google is a quick reference that makes everyone appear 'smart' and it is good for general reference. Yet Google is highly unreliable because anyone can edit it! No serious researcher will use Google as a reliable authority.
so....Where are the links?
Also....Why would many in an agrarian society need to be able to fluently write? Even needing to sign their name would likely be a rare event. It is entirely possible for a person to be able to read and not be able to, or be comfortable with writing.