An event that happens every other year is called a "biennial" event. This term is derived from the Latin "biennium," meaning "two years." Such events can include things like festivals, conferences, or exhibitions that occur once every two years.
A triennial event happens every three years.
I think you are asking about a census.
I think you are asking about a census.
Pre-, then add name of event.
An annual event
weekly
Annual.
An event that occurs every 100 years is called a "centennial" event. The term "century" can also be used to describe this time span, and events that take place at this interval are often celebrated or noted for their significance. In some contexts, such as anniversaries, the term "centenary" is also appropriate.
they call for a special election to fill the vacancy.
Something that happens often is referred to as "frequent." This term indicates that an event or occurrence takes place repeatedly within a given time frame. Other synonyms include "common" or "regular," depending on the context in which it is used.
Bloodbath
wat i did wuz go to the pokeathalon dome and do every event thing and then he'll call