Here are some charts I put together some time ago...
Year Average Publishers Percent Change
1945 "127,478"
1946 "158,034" 19.34%
1947 "181,071" 12.72%
1948 "230,532" 21.46%
1949 "279,421" 17.50%
1950 "328,572" 14.96%
1951 "384,694" 14.59%
1952 "426,704" 9.85%
1953 "468,106" 8.84%
1954 "525,924" 10.99%
1955 "570,694" 7.84%
1956 "591,556" 3.53%
1957 "653,273" 9.45%
1958 "717,088" 8.90%
1959 "803,482" 10.75%
1960 "851,378" 5.63%
1961 "884,587" 3.75%
1962 "920,920" 3.95%
1963 "956,648" 3.73%
1964 "1,001,870" 4.51%
1965 "1,034,268" 3.13%
1966 "1,058,675" 2.31%
1967 "1,094,280" 3.25%
1968 "1,155,826" 5.32%
1969 "1,256,784" 8.03%
1970 "1,384,782" 9.24%
1971 "1,510,245" 8.31%
1972 "1,596,442" 5.40%
1973 "1,656,673" 3.64%
1974 "1,880,713" 11.91%
1975 "2,062,449" 8.81%
1976 "2,138,537" 3.56%
1977 "2,117,194" -1.01%
1978 "2,086,698" -1.46%
1979 "2,097,070" 0.49%
1980 "2,175,404" 3.60%
1981 "2,247,486" 3.21%
1982 "2,347,334" 4.25%
1983 "2,501,722" 6.17%
1984 "2,680,274" 6.66%
1985 "2,865,183" 6.45%
1986 "3,063,289" 6.47%
1987 "3,237,751" 5.39%
1988 "3,430,869" 5.63%
1989 "3,624,773" 5.35%
1990 "3,846,811" 5.77%
1991 "4,071,954" 5.53%
1992 "4,289,737" 5.08%
1993 "4,483,900" 4.33%
1994 "4,695,111" 4.50%
1995 "4,950,344" 5.16%
1996 "5,167,258" 4.20%
1997 "5,353,078" 3.47%
1998 "5,544,059" 3.44%
1999 "5,653,987" 1.94%
2000 "5,783,003" 2.23%
2001 "5,881,776" 1.68%
2002 "6,047,997" 2.75%
2003 "6,184,046" 2.20%
2004 "6,308,341" 1.97%
2005 "6,391,500" 1.30%
2006 "6,455,415" 1.00%
2007 "6,513,514" 0.90%
2008 "6,552,595" 0.60%
2009 "6,578,805" 0.40%
2010 "6,587,029" 0.13%
2011 "6,567,268" -0.30%
2012 "6,534,431" -0.50%
2013 "6,488,690" -0.70%
2014 "6,423,803" -1.00%
2015 "6,340,294" -1.30%
2016 "6,245,190" -1.50%
2017 "6,139,021" -1.70%
2018 "6,016,241" -2.00%
2019 "5,877,867" -2.30%
2020 "5,725,043" -2.60%
2021 "5,564,742" -2.80%
2022 "5,397,799" -3.00%
2023 "5,219,672" -3.30%
2024 "5,036,983" -3.50%