I think by Delta you mean sales growth? and the 119% refers the Dec-13 sales growth on prior corresponding period? Assuming I've understood you correctly, keep in mind that Jun-14 half NAN managed only 12.72% sales growth, for an FY14 average of 44.25%. Also, it's much easier for a business to achieve 40% sales growth coming off a small base, but as the business gets larger and larger it gets harder to achieve those same rates. Hence, the danger in extrapolating historical growth rates into the future.
That being said, I do think that NAN will achieve >20% sales growth over the next few years. As I mentioned previously, I incorporated a 20% sales growth rate into my 'bear case' scenario, which if it were to occur, I estimated I'd lose 9% p.a based on a 78c purchase price over the next few years. Obviously to invest, I think NAN will exceed those forecasts and I'll stand to make a tidy gain. My post was in response to your post "NAN can't lose unless the result has no growth" and my intention was to illustrate that NAN can indeed 'lose' even if it grows sales.
I agree with your point regarding exchange rates. A growing business is likely to experience a higher portion of their sales later in the period, and the dollar did face an accelerating decline during the Dec half. The point being based on averages there would be a FX translation benefit. For completeness, the monthly exchange rates I used were:
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