create implication 1980 (43) -> 20th_century (1486)
create implication 1981 (16) -> 20th_century (1486)
create implication 1982 (25) -> 20th_century (1486)
create implication 1983 (47) -> 20th_century (1486)
create implication 1984 (44) -> 20th_century (1486)
create implication 1985 (52) -> 20th_century (1486)
create implication 1986 (24) -> 20th_century (1486)
create implication 1987 (40) -> 20th_century (1486)
create implication 1988 (47) -> 20th_century (1486)
create implication 1989 (113) -> 20th_century (1486)
create implication 1990 (137) -> 20th_century (1486)
create implication 1991 (118) -> 20th_century (1486)
create implication 1992 (73) -> 20th_century (1486)
create implication 1993 (279) -> 20th_century (1486)
create implication 1994 (306) -> 20th_century (1486)
create implication 1995 (348) -> 20th_century (1486)
create implication 1996 (424) -> 20th_century (1486)
create implication 1997 (672) -> 20th_century (1486)
create implication 1998 (948) -> 20th_century (1486)
create implication 1999 (1021) -> 20th_century (1486)
create implication 2000 (1213) -> 20th_century (1486)