The following data showed the most recent (4th quarter of 2009) NCLEX testing volume and the associated passing rates.
NCSBN has also listed the top 5 countries with the highest number of NCLEX Examinees. Topping the list is the Philippines, followed by India, South Korea, Canada and Nigeria.

Below is the NCLEX RN and NCLEX PN Examination passing rates for the year 2009 released by National Council of State Boards of Nursing.
A chart that shows quarterly and yearly volume and pass rate data for the NCLEX-RN and NCLEX-PN examinations.
The data includes the number of candidates taking the NCLEX Examination and the percentage [...]

CHICAGO – The National Council of State Boards of Nursing, Inc. (NCSBN) voted on Dec. 10, 2009, to raise the passing standard for the NCLEX-RN Examination (the National Council Licensure Examination for Registered Nurses). The new passing standard is -0.16 logits on the NCLEX-RN logistic scale, 0.05 logits higher than the previous standard of -0.21. [...]

The following data showed the most recent (1st quarter, 2nd quarter and 3rd of 2009) NCLEX testing volume and the associated passing rates.
NCSBN has also listed the top 5 countries where nurses were educated outside the US and who are taking the NCLEX examination in hopes of obtaining nursing employment in the United States [...]

The NCLEX-RN examination is administered to the candidate by Computerized Adaptive Testing (CAT).
What is CAT?

CAT is a method of delivering examinations that uses computer technology and measurement theory. Items go through an extensive review process before they can be used as items on the examination.
Computer technology selects items to administer that match the candidate’s ability. [...]