Unitrade has the following (I'm summarizing) -
Sc 1 - perf 9, dull rose
Sc 5 - perf 11.5-12, whitish paper, rose
Sc 5a - perf 11.5-12, yellowish paper, rose
Sc 5g - compound perf
Sc 5i - perf 11.5-12, whitish paper, deep rose
So if yours is on whitish paper, it is #5, although looks a little yellowish to me (of course, hard to tell from a scan).
Here are two of mine for comparison - first is 5g, with compound perfs on yellowish paper, 2nd is 5 on whitish paper.