This graph of unprovoked shark attacks in the world from 1960 through 2016 also shows the portion occurring in the United States for comparison.
The drop in recorded attacks in 1969 is a result of a loss of funding to support the ISAF, and hence less effort reporting and organizing of attacks (see the History of the International Shark Attack File). The apparent increase in attacks after 1987 is in part an artifact of the ISAF moving to the Florida Museum of Natural History, resulting in an increased scope of coverage and reporting of attacks. The apparent increase in attacks after 1993 is in part an artifact of a breakthrough in communication with Volusia County (FL) emergency responders and lifeguards, resulting in the reporting of a greater number of minor attacks that had previously gone unreported.
Unprovoked Shark Attacks in the World vs. the United States