Since Derek de Solla Price's Little Science - Big Science (1963) it is known that the number of scientific publications grows exponentially. It's also known that more and more publications are published electronically. I am looking for studies that compare the actual growth of both. How does the fraction of digital publications compared to printed publications rise?
Sure an answer depends on where one draws the line between a publication and just any digital content. Any actual studies that try to measure the growth based on some definition? By the way I am not interested in the amout of information, but in the number of publications because libraries primarily collect publications.