*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978001001
1979000000
1980002002
1981002002
1982000000
1983000000
1984000000
1985000000
1986011002
1987010001
1988003003
1989072009
1990010001
1991013004
1992010001
1993010001
1994032005
1995000000
1996000000
1997021003
1998041005
1999000000
2000010001
2001001001
2002012003
2003010001
2004002002
2005072009
2006014005
2007052007
2008001001
2009030003
2010004004
2011031004
201201810019
2013021003
2014000000
2015001001
2016000000
2017000000
Total0644000104