数据如下所示
input str12 Stkcd float date str18 Accper str13 ShortName str12 Typrep double monetaryamount byte stinvest double totasset float numr long Stkcd_ float(money money_)
"000002" 17531 "2007-12-31" "万科A" "A" 17046504584.31 0 100094467908.29 17046504448 2           . .
"000002" 17897 "2008-12-31" "万科A" "A" 19978285929.92 0 119236579721.09 19978285056 2 17046504448 .
"000002" 18262 "2009-12-31" "万科A" "A"  23001923830.8 0 137608554829.39 23001923584 2 19978285056 .
"000002" 18627 "2010-12-31" "万科A" "A" 37816932911.84 0 215637551741.83 37816934400 2 23001923584 .
"000002" 18992 "2011-12-31" "万科A" "A" 34239514295.08 0 296208440030.05 34239514624 2 37816934400 .
"000002" 19358 "2012-12-31" "万科A" "A" 52291542055.49 0 378801615075.37 52291543040 2 34239514624 .
"000002" 19723 "2013-12-31" "万科A" "A" 44365409795.23 0 479205323490.54 44365410304 2 52291543040 .
"000002" 20088 "2014-12-31" "万科A" "A" 62715253375.94 0 508408755415.65 62715252736 2 44365410304 .
"000002" 20453 "2015-12-31" "万科A" "A" 53180381016.34 0 611295567689.29 53180379136 2 62715252736 .
"000002" 20819 "2016-12-31" "万科A" "A" 87032118210.63 0 830674213924.14 87032119296 2 53180379136 .
end
format %td date


已经使用xtset设置年份和时间（xtset Stkcd_ date)
然后根据Stkcd分组滞后时 就全部出现缺失值 bys Stkcd: gen money_=l.monetaryamount