??????????????
??????????????????????????circulation)???
??????:??????????????????????????????
??????????????????30???????68%,?????????????????????98%?????????????????????????18%,????????????154%
??johns hopkins??????????????????????????,??????????????????,???????75????????????30??????????40%
???????david thiemann???:??????????????????????????????,??????????????????????????,???????????????????????????????????,?1/3?75??????????????,??,????????攖hiemann?????????????????
???????????7,864?????65??86????????????????????,????????????5,191????65??75???,2,673???????76??86???
?????????????????,??????????????????
?????????????????
