As noted on the NYS Education Dept. site, "Chapter 655 of the Laws of 1987 (which amended Section 215-a of State Education Law) requires the Board of Regents and the State Education Department to submit an annual report to the Governor and the Legislature with respect to 'enrollment trends; indicators of student achievement in reading, writing, mathematics, science, and vocational courses; graduation, college attendance and employment rates [...][and] information concerning teacher and administrator preparation, turnover, in-service education and performance.'"

Copies of the full report for the past 5 years can be viewed/downloaded at:
http://www.emsc.nysed.gov/irts/655report/home.html

Here is a table with the most recent percentages :
http://www.emsc.nysed.gov/irts/educationstats/edstats-05/table4.html

here is the table of contents for the report where it is found:
http://www.emsc.nysed.gov/irts/educationstats/edstats-05/toc.htm

The stats include "racial" data (ie. Black/White/Hispanic/Other) rather than "nationality." This may well be the only "officially" collected data. Would this be sufficient for your needs? I will continue to poke around tonight; further info on how well this answers your question will help me out.