*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970100001
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981000000
1982000000
1983000000
1984000000
1985000000
1986000000
1987000000
1988001001
1989000000
1990000000
1991000000
1992001001
1993000000
1994000000
1995001001
1996000000
1997002002
1998002002
1999000000
2000001001
2001003003
2002004004
2003002002
2004011002
2005001001
2006001001
2007006006
2008002002
2009001001
2010005005
2011001001
2012000000
2013000000
2014000000
2015000000
2016001001
2017001001
Total11370039