When I first heard this slogan I assumed they meant that Sanka had only 3% of the caffeine of regular coffee. But now I assume they meant it was 3% caffeine by weight.
After all, 2% milk has 2% fat. Regular milk has 3.5% fat, so 2% sounds very fat free but actually has over half the fat remaining.
That is the equivalent of 96.18% less caffeine that regular instant coffee. If it was 3% of the weight, decaffeinated would have 60 milligrams per serving, or more than regular coffee. That does not compute.