*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973001001
1974000000
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981000000
1982000000
1983000000
1984000000
1985000000
1986010001
1987001001
1988001001
1989000000
1990000000
1991001001
1992000000
1993000011
1994000011
1995001001
1996001001
1997001001
1998000000
1999001001
2000000000
2001000000
2002001001
2003000000
2004000000
2005001001
2006000000
2007001001
2008002002
2009000000
2010000000
2011000000
2012000000
2013001001
2014001001
2015002002
2016000000
2017000000
Total01170220