Bar charts are proportional to record count, and scaled.

Publication Year	Count	Percent
1957	3	0.5	.
1958	15	2.3	.
1959	19	2.9	.
1960	23	3.5	.
1961	16	2.4	.
1962	11	1.7	.
1963	13	2.0	.
1964	13	2.0	.
1965	22	3.4	.
1966	20	3.0	.
1967	24	3.7	.
1968	17	2.6	.
1969	22	3.4	.
1970	14	2.1	.
1971	22	3.4	.
1972	11	1.7	.
1973	14	2.1	.
1974	12	1.8	.
1975	23	3.5	.
1976	9	1.4	.
1977	14	2.1	.
1978	17	2.6	.
1979	11	1.7	.
1980	14	2.1	.
1981	17	2.6	.
1982	9	1.4	.
1983	12	1.8	.
1984	9	1.4	.
1985	11	1.7	.
1986	7	1.1	.
1987	10	1.5	.
1988	14	2.1	.
1989	7	1.1	.
1990	12	1.8	.
1991	9	1.4	.
1992	10	1.5	.
1993	4	0.6	.
1994	6	0.9	.
1995	9	1.4	.
1996	15	2.3	.
1997	7	1.1	.
1998	6	0.9	.
1999	6	0.9	.
2000	5	0.8	.
2001	10	1.5	.
2002	4	0.6	.
2003	5	0.8	.
2004	11	1.7	.
2005	9	1.4	.
2006	10	1.5	.
2007	3	0.5	.
2008	11	1.7	.
2009	7	1.1	.
2010	15	2.3	.
2011	7	1.1	.

Items: 55