When the real numbers are extended with plus and minus infinity, as in the IEEE-754 or IEEE-754-2008 standards for floating point arithmetic, the result of dividing an infinity by an infinity is not mathematically well-defined. That's why both of those IEEE standards add special NaN values, where NaN means "not a number". So NaN would be a better answer than 1/1.
The formula I gave you is more useful because it tells you the approximate ratio of primes to non-primes in the range from 0 to x.
If you take the limit of that formula as x increases without bound ("goes to infinity" in the misleading vernacular), then you'll find that the ratio of primes to non-primes becomes arbitrarily close ("converges") to zero. Hence zero would be an even better answer than NaN or 1/1, if you're asking about the ratio taken over all natural numbers.
So I could have answered your question by writing "0", but I thought the formula I gave would be more informative, and it already implies 0 in the limit as x increases toward infinity.
[size=-1](Although this post may violate Rule 11, the moderators might allow it to stand long enough for you to read it, or they might split our posts into a new thread.)[/size]