What is the prevalence rate of the patients' diseases started on 9th May 2014?
diseases started on 9th May 2014 refer to DESCRIPTION from conditions where START = '5/9/2014';
SELECT T2."PREVALENCE RATE" FROM conditions AS T1 INNER JOIN all_prevalences AS T2 ON lower(T1.DESCRIPTION) = lower(T2.ITEM) WHERE T1.START = '2014-05-09'