<prompt> Translate the following text to EnglishKiwango cha wastani cha usambazaji huu, ambayo ni karibu 331,000, inachukuliwa kama makadirio ya mwelekeo wa msingi wa WTP ili kuepuka kesi ya CB inayohusiana na PM.  <response>: The mean of this distribution, which is about 331,000 1999, is taken as the central tendency estimate of WTP to avoid a PM-related case of CB. 