1) Rapid inflation
2) Rapid growth in a profitable (even labor-light) industry
3) Relatively increased exporting
4) Population increase
4) A combination of these factors
The general rule is that x/70 is the amount of time it takes for something to double, where x is the percent increase over time. For example, if my GDP grows 1% a month, it'll take 70 months for it to basically double (1.01^70=2.007). You wanted 5 years for 300%, right? That's 25% annual growth. With recent developments and the Western inflation, I think that's attainable. Toss in normal growth with larger demand and some inflation, and you're well on your way. Remember that GDP is not dependent on what is purchased, rather being what is produced. If you made bicycles and produced 365 in one year but only sold 300, your annual production is still 365. (82.2% sold) What has to be realized, though, is that the year following you'll be down 65 units produced. If you do 365 again and sell 430 (365+65), your annual production is still 365. (117.8% produced are sold) That'd be no change at all between the two years, since only 365 were made regardless of how many sold. Now fast forward another year, and say that 430 were produced and subsequently sold the very same year. Those 430 will represent a 17.8% increase in production but sales will remain flat between the two years. That is very oversimplified. In those three years, say your price for each bicycle was $100. If that price increased to $110, your part of the GDP would increase 10%. If the price was $50, your part of the GDP would decrease 50%. It's based on today's value.