Years 1930s 1931 1 1935 1 1936 2 1940s 1940 1 1943 1 1945 1 1947 2 1949 2 1950s 1950 2 1951 8 1952 4 1953 4 1954 5 1955 12 1956 9 1957 22 1958 14 1959 24 1960s 1960 20 1961 17 1962 37 1963 34 1964 38 1965 52 1966 35 1967 48 1968 48 1969 33 1970s 1970 29 1971 31 1972 34 1973 16 1974 12 1975 18 1976 16 1977 8 1978 21 1979 53 1980s 1980 36 1981 28 1982 26 1983 31 1984 24 1985 30 1986 31 1987 42 1988 28 1989 7 1990s 1990 16 1991 24 1992 20 1993 33 1994 28 1995 29 1996 37 1997 46 1998 30 1999 48 2000s 2000 61 2001 31 2002 9 2003 24 2004 33 2005 24 2006 18 2007 22 2008 31 2009 53 2010s 2010 80 2011 78 2012 83 2013 139 2014 116 2015 137 2016 433 2017 2308 2018 2637 2019 3671 2020s 2020 1902 2021 1535