*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975001001
1976001001
1977000000
1978000000
1979001001
1980001001
1981000000
1982000000
1983000000
1984000000
1985000000
1986001001
1987001001
1988000000
1989000000
1990000000
1991001001
1992000000
1993002002
1994000000
1995000000
1996000000
1997000000
1998000000
1999000000
2000000000
2001001001
2002000000
2003000000
2004000000
2005001001
2006003003
2007000000
2008000000
2009000000
2010001001
2011000000
2012001001
2013001001
2014002002
2015001001
2016000000
2017000000
Total00200020