Knowledge and information is everywhere these days - and the internet
has given us access to the most powerful library in the world. I am
sure that in a single day, indeed, in a single edition of a newspaper,
we have access to more information than most people aquired in their
entire lifetime just...how many years ago?

Your answer, in a nutshell, is summed up nicely in this quote:

"A weekday edition of The New York Times contains more information
than the average person was likely to come across in a lifetime in
seventeenth-century England."

This memorable (but ultimately unprovable) quote has an interesting
history in its own right. The quote, in various forms, is widespread
on the Web. It appears that the original source was a book called "The
Cult of Information," by Theodore Roszak, a widely acclaimed author
who is a Professor of History at California State University. Dr.
Roszak's book was originally published in 1986; an updated second
edition came out in 1994. The quote is often misattributed to Richard
Saul Wurman, who helped to popularize it.

The quote above is a striking one, but it should be taken with a grain
of salt, even though it originated with a history professor. In point
of fact, no one really knows how much information the average person
encountered in the seventeenth century; it is difficult enough to make
such estimates in relation to modern times. But it is certainly true
that modern readers are bombarded by immense amounts of information,
in comparison to readers of the past.

Some info on the origins of the quote:

"It is hard to conceive a better way to approach the theme than with
the well-known quote: 'a weekday edition of The New York Times
contains more information than the average person was likely to come
across in a lifetime in seventeenth-century England'...

The above quote appears in numerous works by distinguished
researchers. In the article System Overload, published in Time
(12.9.96 pp.44-45), it is stated that the figure comes from Richard
Saul Wurman?s 1989 book Information Anxiety. And it is indeed right
there, in the book?s first chapter. Maybe Wurman himself,
world-renowned information architect, arrived to this conclusion in
1989, maybe not. What is true is that many of the works that take
advantage of this 'fact' to impress their readers quote Wurman on it.
And most simply don?t quote anyone at all.

Not less trustworthy, American journalist David Shenk, author of Data
Smog: Surviving the Information Glut, also does not resist the
temptation and includes the same information in his 1997 book (pp.
26-27). But this time the credits first go to Columbia University?s
professor Eli M. Noam, who mentioned the fact in his work Visions of
the Media Age: Taming the Information Monster. Dr. Noam?s source was
The Cult of Information: The Folklore of Computers and the True Art of
Thinking, a book by Theodore Roszak published in 1986, i.e. roughly
three years before Wurman?s book. Surprisingly, not even Shenk - whose
work is most recognised by its accuracy - got the figure from the
original source."

Voxel: The Digital Information
http://www.voxel.com.br/pt/knowledge/the_digital_information/pag02.aspx

A recent use of the New York Times quote and a remark about the
doubling of the amount of information appeared in "Leadership 101:
What Every Leader Needs to Know," by John C. Maxwell:

"Did you know that more new information has been produced in the last
thirty years than in the previous 5,000? A weekday edition of The New
York Times contains more information than average people in
seventeenth century England were likely to come across in their
lifetime. The amount of information available in the world has doubled
in the last five years, and it keeps doubling."

(Source: "Leadership 101: What Every Leader Needs to Know," by John C.
Maxwell. Nelson Books, 2002. ISBN: 0785264191)

Regarding the doubling of the amount of information, things are
speeding up. A groundbreaking study from the University of California
at Berkeley had this to say in 2003:

"We estimate that the amount of new information stored on paper, film,
magnetic, and optical media has about doubled in the last three
years."
 
UCal Berkeley: How Much Information? 2003 (Executive Summary)
http://www.sims.berkeley.edu/research/projects/how-much-info-2003/execsum.htm

The entire text of the "How Much Information" project is available as
a .pdf file. It's a whopper (112 pages), so it takes quite a while to
download (one is tempted to say that this is too much information).

UCal Berkeley: How Much Information? 2003 (Printable Report) 
http://www.sims.berkeley.edu/research/projects/how-much-info-2003/printable_report.pdf

Google search strategy:

Google Web Search: "newspaper contains more information than"
://www.google.com/search?hl=en&ie=UTF-8&q=%22newspaper+contains+more+information+than%22

Google Web Search: "amount of information" growth
://www.google.com/search?hl=en&ie=UTF-8&q=%22amount+of+information%22+growth

Google Web Search: "quantity of information" "average person"
://www.google.com/search?hl=en&ie=UTF-8&q=%22quantity+of+information%22+%22average+person%22

Google Web Search: "information OR data explosion"
://www.google.com/search?hl=en&ie=UTF-8&q=%22information+OR+data+explosion%22

I hope this is helpful. If anything is unclear, or if a link doesn't
work for you, please request clarification; I'll be glad to offer
further assistance before you rate my answer.

Best regards,
pinkfreud