????????????????????????????

????5??21???????????????????????????????????????????????20%???????8.89?????
?????????????10??35?????????9.74??????μ?1.66???????????14.59%??
?????????????μ????????????????????????????Johnson&Weaver???????????????????????????????????????????????????????????
?????????????????????????????????3020?????????????8.4%?????????14.9%?????????240???????????47.8%???????66.7%??
??????????????——????????????????????????????????????????2120?????????????8.5%?????????14.7%????Щ???????????????????????????
????????2015??3??31??????????????????2014??12??31??495?????????488?????
????????2015?????????????????????????????39???????ж????????????????????????????????????