1987—Subsec. (c). Pub. L. 100–4 substituted “1990” for “1985”.

1981—Subsec. (c). Pub. L. 97–117 substituted “September 30, 1985” for “September 30, 1982”.

1977—Pub. L. 95–217 designated existing provisions as subsec. (a) and added subsecs. (b) and (c).