A paper in the 14 August issue of Science* reported that the average number of scientific papers read by scientists per year has increased more or less steadily since 1977. According to the following graph in the paper, in 2005, the last year for which data were available, the average was about 280 papers/year.
Modified from Fig. 2 in Renear & Palmer (2009).
If the trend has been continuing at the same rate, the annual average must have exceeded 300 papers by now.
I got curious and made a list of the papers I read during a 4-week period between 24 August and 20 September. Renear & Palmer do not explain how the numbers they cite had been obtained and how much of a paper one had to read to count it as "read". I counted a paper as read if I read about 2/3 or more of it.
My 4-week total was 21 papers. If I maintained the same pace throughout the year, that would add up to 273 papers. So I am slightly below the estimated average for 2009.
Of those 21 papers, 9, or ~43%, were about mollusks. Of course, many of the rest were indirectly related or applicable to my research with snails and slugs.
*Allen H. Renear and Carole L. Palmer. 2009. Strategic Reading, Ontologies, and the Future of Scientific Publishing. Science 325:828-832. Abstract