In this task, we ask you to write an answer to a question that involves event "frequency", which refers to how often an event is likely to be repeated. For example, "taking showers" typically occurs ~5 times a week, "going to Saturday market" usually happens every few weeks/months, etc. Note that a lot of the questions could have more than one correct answer. We only need a single most-likely answer. Please try to keep your "answer" as simple as possible. Concise and simple "answer" is preferred over those complex and verbose ones.
Q: Sentence: He succeeds James A. Taylor, who stepped down as chairman, president and chief executive in March for health reasons. 
Question: How often are chief executives typically replaced?
A: 
when someone steps down or gets fired.