I had a look on the web and came across an interesting essay at:
A fascinating factoid is that if you take numbers of books deposited in the Library of Cambridge per year as a measure it appears that knowledge has been doubling every 33 years for THE LAST 500 YEARS. Of course this is just one line of evidence, but it is remarkable that this relationship stands up so strongly for so long. People can say the Internet will make all changes much, much quicker, but its interesting despite lots of other high tech changes over the last half millenium this particular rate of increase has stayed so constant.
Editor: PSYCHE: An International Journal of Research on Consciousness Board Member: The Association for the Scientific Study of Consciousness http://psyche.cs.monash.edu.au/ http://www.phil.vt.edu/ASSC/