*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970004004
1970000000
1971001001
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981001001
1982000000
1983000000
1984001001
1985000000
1986000000
1987000000
1988000000
1989000000
1990000000
1991001001
1992000000
1993000000
1994000000
1995000000
1996000000
1997000000
1998002002
1999000000
2000000000
2001000000
2002002002
2003000000
2004002002
2005001001
2006000000
2007001001
2008003003
2009001001
2010003003
2011000000
2012000000
2013000000
2014000000
2015000000
2016000000
2017000000
Total00230023