*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979000101
1980000000
1981000000
1982000000
1983000000
1984000101
1985000000
1986000000
1987100001
1988000000
1989100001
1990000000
1991000101
1992200507
1993100203
1994200305
1995100203
1996100001
1997100102
1998100001
1999100304
2000100405
2001100203
2002310307
2003200406
2004100102
2005010102
2006200305
2007100506
2008000808
2009200305
2010000303
2011200507
2012200305
2013100001
2014000000
2015000101
2016100001
2017000000
2018000000
Total312065098