To ensure equal representation, district populations are required to be at least approximately equal to one another. A complete count of the U.S. population is conducted once every ten years, in the decennial census. Following release of the census data, one of the first redistricting tasks is to calculate the new ideal district population for each legislative body. For statewide redistricting using single member districts, the ideal district population is simply the state's population divided by the total number of districts. Once the new ideal population is know, population deviation maps and reports can be created to help assess how far out of balance existing district plans have become over the course of the previous decade.