Graph using data obtained from the USPTO website showing the total number of patents granted per year since 1971 against the number of "software patents" granted per year. Software patents were identified using a technique proposed by Bessen & Hunt and described in List of software patents.

Specifically, the following search was run in the USPTO patent database for values of x between 1971 and 2006

ISD/(1/1/x->1/1/x+1)

AND SPEC/(software OR (computer AND program))

AND APT/1

ANDNOT TTL/(chip OR semiconductor OR bus OR circuit OR circuitry)

ANDNOT SPEC/(antigen or antigenic OR chromatography)

to obtain the number of software patents.

Then a similar search was run:

ISD/(1/1/x->1/1/x+1)

AND APT/1

to obtain the total number of patents over the same period.

The actual obtained data by this method and illustrated in the graph was as follows:

• 1971 - 550 out of 78317
• 1972 - 668 out of 74810
• 1973 - 683 out of 75678
• 1974 - 683 out of 76278
• 1975 - 684 out of 72000
• 1976 - 725 out of 70226
• 1977 - 838 out of 65269
• 1978 - 845 out of 66102
• 1979 - 783 out of 49969
• 1980 - 1019 out of 61819
• 1981 - 1210 out of 65771
• 1982 - 1319 out of 57888
• 1983 - 1358 out of 56860
• 1984 - 1888 out of 68329
• 1985 - 2357 out of 71661
• 1986 - 2530 out of 70860
• 1987 - 3384 out of 82952
• 1988 - 3326 out of 77924
• 1989 - 4751 out of 95537
• 1990 - 4555 out of 91882
• 1991 - 5080 out of 96511
• 1992 - 5579 out of 97444
• 1993 - 6425 out of 98342
• 1994 - 7579 out of 101676
• 1995 - 8571 out of 101419
• 1996 - 10818 out of 109645
• 1997 - 11534 out of 111984
• 1998 - 18415 out of 147519
• 1999 - 19457 out of 153489
• 2000 - 20730 out of 157493
• 2001 - 23347 out of 168030
• 2002 - 24550 out of 167325
• 2003 - 27362 out of 169022
• 2004 - 30113 out of 164290
• 2005 - 28900 out of 143805
• 2006 - 40874 out of 173776
• 2007 - 38874 out of 185710 (not depicted in graph)