You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is The prevalence of dental caries in a community in the year 2000 and 2003 was 18% and 38% respectively. The incidence of caries for the same population in three years would be: and explain in detail?
Hint:
Incidence  = No. of new cases in a specified time (38-18 = 20%)
Prevalence = Incidence x Duration.  
Incidence = Prevalence / Duration = P/D.