Let $X, Y$ be positive real numbers, and let $p_1, ... p_n$ be the primes less than $Y$. How many subsets $S$ of the integers from 1 to $n$ are there such that the product of the $p_i$'s with $i$ in $S$ is less than $X$, as a function of $X,Y$?

Clearly, if $X$ is sufficiently large relative to $Y$, then all choices of $S$ work. I am interested in the case when $Y$ is not too small compared to $X$, say $Y = X/C$ for some fixed positive constant $C$ larger than 1.