The Lemelson-MIT Invention Index is "an annual survey of Americans' perceptions about inventing and innovating," and on January 21, 2003, the results for 2003 were released. According to this article, the one invention that respondents said they could not live without was the toothbrush, which was found to be more important than the PC, the automobile, the cellular phone, and the microwave oven. Specific results are reported in the press release. Also on this Web site are links to the previous seven surveys. The focus of each year's study usually varies, and it is interesting to note changes in peoples' perceptions over the years.