What is the average prime numbers we've found till now? When you count from 0 to 100 you have 25% prime numbers. Till now the largest prime consists of $2^{74,207,281}-1$ numbers. But is known what the average is till now?
With average I just mean the amount of prime numbers comparing to the total numbers till the value of the last prime number. So from 1 to 100 there are 25 prime numbers. Probably the average is decreasing. I don't know how many prime numbers there are between 100 and 200 but imagine that there are 15 prime numbers. So from 1 to 200 we have an average of 25+15=40 on a total of 200 numbers so the average is dropped to 20%. If you go on till the last known prime number (2^{74,207,281}-1) what would then be the average on the total numbers till that last prime number.
I suppose because there is an infinite amount of prime numbers the average will drop close to zero, supposing too that the amount of prime numbers is more and more decreasing
I don't think this is a soft question because I think there is an objective answer on it possible. But how to calculate?
 A: There  have been various attempts at approximating the Prime Counting Function $\pi(x)$ which gives the number of primes $\leq x$. A simple approximation is
$$\pi(x)\sim \frac{x}{\ln x}$$
We can get an approximation of the long-run frequency of primes by looking at:
$$\lim_{n \to \infty} \frac{\pi(n)}{n} \approx \lim_{n \to \infty} \frac{n}{n\ln(n)} = \lim_{n \to \infty} \frac{1}{\ln n} = 0  $$
Since the number of primes grows at a sub-linear rate (at least asymptotically), then they become exceedingly rare as a fraction of the numbers up to $N$.
As for the "average value" of the primes, it has been shown that there are infinitely  many primes, so the average value of all primes is $\infty$. 
A: We do not have $2^{74,207,281} − 1$ prime numbers by now. Instead, the largest number about which we know that it is a prime is $p=2^{74,207,281} − 1$. The actual number of primes of to $p$ should be around $p/\ln p$, but we do not "know" all of these in the sense that each of them has been computed by someone. Rather, those record-breaking primes are found by trying numbers matching patterns that are much rarer than being prime 8and that's also why we can even write done the 22,338,618 digit number $p$ with just a handful of symbols). Even if we had managed to write a prime on every single particle of the known Universe, that would mean we "know" only $10^{80}$ primes. Even then, the largest known prime $p$ contributes $p/10^{80}\approx 10^{22,338,538}$ to the average. On the other hand, the next largest known prime number today is $2^{57,885,161} – 1$, which is smaller than $p$ by a factor so much larger that $10^{80}$ that for all practical purpuses we can say that the average of all known primes is just $2^{74,207,281} − 1$ divided by the number of known primes and hence it is a number somewhere between $10^{22,338,538}$ and (because certainly more than $10^8$ primes are known) $10^{22,338,610}$.
