|ISO3166-1 Codes||UM, UMI, 5811|
“Both the US and the Kingdom of Hawaii annexed Johnston Atoll in 1858, but it was the US that mined the guano deposits until the late 1880s. Johnston and Sand Islands were designated wildlife refuges in 1926. The US Navy took over the atoll in 1934. Subsequently, the US Air Force assumed control in 1948. The site was used for high-altitude nuclear tests in the 1950s and 1960s. Until late in 2000 the atoll was maintained as a storage and disposal site for chemical weapons. Munitions destruction, cleanup, and closure of the facility were completed by May 2005. The Fish and Wildlife Service and the US Air Force are currently discussing future management options; in the interim, Johnston Atoll and the three-mile Naval Defensive Sea around it remain under the jurisdiction and administrative control of the US Air Force.”
CIA's The World Factbook (2013)5
As a territory of the USA I do not have many specific statistics for this territory in its own right.
There isn't much information in the database for Johnston Atoll, most likely because it is either a part of another country (i.e., a territory or posession) and therefore most international statistics are counted for the country as a whole, or, this is such an exotic place that little data exists about it.