想用stata将wide数据转换成long我打了reshape long sheet36, i(countryname) j(year)
但是stata显示，求大侠释疑
我把原数据放入附件 请各位帮忙看看

no xij variables found
You typed something like reshape wide a b, i(i) j(j).
reshape looked for existing variables named a# and b# but could not find any.Remember this picture:

long wide
+---------------+ +------------------+
| i j a b | | i a1 a2b1 b2 |
|---------------| <--- reshape ---> |------------------|
| 1 1 1 2 | | 1 1 3 24 |
| 1 2 3 4 | | 2 5 7 68 |
| 2 1 5 6 | +------------------+
| 2 2 7 8 |
+---------------+

long to wide: reshape wide a b, i(i) j(j) (j existing variable)
wide to long: reshape long a b, i(i) j(j) (j new variable)


原数据

CountryName	1960 [YR1960]	1961 [YR1961]	1962 [YR1962]	1963 [YR1963]	1964 [YR1964]
Argentina	2.685281	2.432308	2.328961	2.285788	2.23608
Australia	2.783396	2.493808	2.922755	2.390362	2.424252
Brazil	5.204268	5.102537	5.071378	5.018287	4.916381
China	4.935495	2.053596	3.873678	5.493641	5.327344
France	2.447048	2.543971	2.86061	3.354723	3.186223
Germany	1.251659	1.20737	0.970049	1.015019	0.895597
India	2.347275	2.589566	3.0413	3.063189	3.09739
Indonesia	3.998054	4.01274	4.02288	4.048851	4.074228
Italy	2.836401	1.498807	1.506833	1.551287	1.636027