Interest of 1% to 2% with $500 increasing to $1000 is a 100% increase. In the same way 2% to 3% is $1000 increasing to $1500 is a 50% increase. Im confused by exactly what it is you're asking. If you ignore the percentage sign in real terms you're talking about proportional increases being larger for lower base inflation rates, hence a financial crisis is a scary concept in the modern day.