请问在stata中，按照公司股票代码和年份计算每一公司本年营业收入与上年营业收入的比值该怎么解决？<br>
如下图分别为股票代码 年份 营业收入<br>
2 "2009-12-31"  48881013143.49
<br>
2 "2010-12-31"  50713851442.63
<br>
2 "2011-12-31"  71782749800.68
<br>
2 "2012-12-31" 103116245136.42
<br>
2 "2013-12-31" 135418791080.35
<br>
2 "2014-12-31" 146388004498.44
<br>
2 "2015-12-31"  195549130020.9
<br>
2 "2016-12-31" 240477236923.34
<br>
2 "2017-12-31" 242897110250.52
<br>
2 "2018-12-31" 297679331103.19<br>
用来计算成本粘性的，拜托了！