Annual subscription fees (shown in green for a full personal subscription) have traditionally been a major source of income. Author-paid page charges (blue) and submission fees (red) also contribute: the price of a 9-page black-and-white article is shown. Note that fees for color figures are not factored into the data presented and that the pricing scheme introduced in June 2003 charges per word and per figure rather than per page. Color pages once cost as much as $2,000 each (in 1996) but are now much more affordable. Also note that for many years the price per page increased dramatically if more than 8 pages were required.