Calculate score for multiple variables to "score" zip codes

I have done this analysis before but want to open it up to the community because I have not considered alternative methods.

I essentially am trying to "score" ZIP codes for how much a ZIP code demands private school and related goods and services. I have data for each ZIP code on...

1. Household income (e.g., % of families earning above certain thresholds
2. Level of education attainment (e.g., % of families earning bachelors, doctorates, etc.
3. Level of private school enrollment (e.g., # and X% of the ZIP code is enrolled in PS
4. Number of high quality public school alternatives

I would like to be able to create a function so that I can enter the values of each ZIP code and then have a result that returns and says demand is X%ile along a curve, but the problem is I don't have a Y variable that is just "private school demand". I can and in the past have used private school enrollment as a proxy, but I am wondering what you all think I should do here.

Thanks very much.

If you don't have the $$y$$, then you can't learn a function which gives you $$\mathbb{E}(y\vert x)$$, plain and simple. Using a proxy measure, as you've done, is probably the next best thing but you open yourself up to problems without knowing how and when the proxy is a bad proxy for the outcome.