Here are yearly totals from the Mathematics Genealogy Project. (This is as of August 2012.)
Year # of Math PhDs known to MGP --------------------------------------------- 1960 593 1961 674 1962 863 1963 1002 1964 1203 1965 1309 1966 1439 1967 1549 1968 1762 1969 1949 1970 2031 1971 1986 1972 2057 1973 1997 1974 1997 1975 1922 1976 1859 1977 1830 1978 1911 1979 1922 1980 1873 1981 1822 1982 1939 1983 2012 1984 1966 1985 2023 1986 2102 1987 2267 1988 2526 1989 2703 1990 2884 1991 3009 1992 3328 1993 3419 1994 3650 1995 3764 1996 4034 1997 4053 1998 4181 1999 4065 2000 4275 2001 3932 2002 3815 2003 3807 2004 3919 2005 4751 2006 4445 2007 4332 2008 4194 2009 3877 2010 3714 2011 3235 2012 1372 ------------------------ Total 1960-2012 139143
For comparison, the total number of records in the MGP at this time is 163611.
Also, this (undated) AMS page says there are 35800 members of the four main U.S. mathematics professional societies.