请看以下数据
code listyr1listyr2 .... listyr_n
1 19901991.... 2013
2 19911992.... 2014
3 19951996.... 2018
4 19981999.... 2021


如何转换成如下的目标数据：
code year
1 1990
1 1991
1 1992
1 1993

省略
1 2013
2 1991
2 1992
2 1993
2 1994

省略
2 2014


我使用reshape long listyr, i(code) j(year)结果显示variable id does not uniquely identify the observations
Your data are currently wide.You are performing a reshape long.You specified i(code) and
j(year).In the current wide form, variable code should uniquely identify the observations.
Remember this picture.
到底怎么用才可以呢（注：code有2046个）