Also, the extent to which seizure statistics from countries constitute all reported national cases, regardless of the final destination of the illicit drug, may vary, making it difficult to assess international drug trafficking.
同时，无论非法药物的最终目的地为何处，各国的缉获数据构成所有上报的国家案件的范围也可能不同，因此很难评估国际贩运情况。