*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
1984000000
1985000000
1986000101
1987100203
1988100506
1989100001
1990000202
1991000404
1992000303
1993000000
1994000505
1995000404
1996000303
1997000404
1998000101
1999000404
2000000101
2001000606
2002000404
2003000606
2004000101
2005000000
2006000202
2007000303
2008000505
2009000202
2010000101
2011000606
2012000000
2013100001
2014000000
2015000000
2016000000
2017000000
2018000000
Total40076080