From the Swets Website:
Every year, Swets collects pricing information from thousands of publishers worldwide. As a helpful, additional budgeting tool for its customers, Swets publishes a Serials Price Increase Report which contains a wealth of data covering thousands of publications. The report is published in stages, with the first appearing in October with monthly updates following until the final, full report is made available in the February of the following year.
An additional historical report, providing an overview of prices from 2001 onwards, is also available for customers and can be downloaded from the same page.
Note: As of 11/8/2011 we were able to download the files direct from Swets WITHOUT having to login as a customer.