The propagation of citations of "A Comparison of Commericial and Military Computer Security Policies"

First published in 1987, Dave D. Clark and Dave R. Wilson's paper "A Comparison of Commericial and Military Computer Security Policies" continues to influence research work. Here is how the citations to it evolved at the Security and Privacy Symposium:
the 1980's
the early 1990's
through the 1990's
the early 2000's
to 2009