I believe it is this limit in quantity that has shot it up that high in value because it's always in demand and due to its limited supply on the market it is always growing in value and other currencies that it is being compared to don't have such limited supply.
The limited quantity of bitcoin is definitely a factor in the growing demand and it is good to see that bitcoin has crossed over 120 billion dollars and it is ranked thirty two in the world index which is really great considering the fact that it is less than ten years old and the major push started less than five years back.