The global quota for employment-based immigrants for a fiscal year, as defined in this subsection, is determined by:
(A) A base level of 140,000, plus
(B) The number calculated under paragraph (2).
Under paragraph (2):
(A) The count for fiscal year 1992 is zero.
(B) For fiscal year 1993, compute the difference, if any, between the established worldwide level in the previous fiscal year under paragraph (1) and the number of visas issued under section 1153(b) of this title during that fiscal year.
(C) For subsequent fiscal years, determine the difference, if any, between the maximum number of visas permissible under section 1153(a) of this title (related to family-sponsored immigrants) in the prior fiscal year and the number of visas issued under that section during that year.