year	rate
1974	2.58
1975	2.37
1976	2.27
1977	2.21
1978	2.07
1979	2.12
1980	2.03
1981	2.01
1982	1.95
1983	1.92
1984	1.93
1985	1.93
1986	1.96
1987	2.03
1988	2.1
1989	2.12
1990	2.18
1991	2.16
1992	2.12
1993	2.1