*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970200103
1970000000
1971000000
1972000000
1973100001
1974000000
1975000000
1976100001
1977100001
1978000000
1979000000
1980000000
1981200002
1982100001
1983000000
1984200002
1985000000
1986100001
1987000000
1988000000
1989100001
1990000000
1991100304
1992200103
1993100001
1994000101
1995000000
1996100001
1997100001
1998200002
1999100001
2000300003
2001900009
2002000202
2003100102
2004100001
2005100001
2006000101
2007300205
2008000000
2009000000
2010000000
2011100102
2012300104
2013000000
2014000000
2015000000
2016000000
2017000000
2018000000
Total430014057