Coreference

1968	1970	1983	1990	2000
	1973	1984	1991	2001
	1974	1985	1992	2002
	1976	1986	1993	2003
	1977	1987	1994	2004
	1978	1988	1995	2005
	1979	1989	1996
			1997
			1998
			1999