*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970011002
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981000000
1982000000
1983000000
1984002002
1985001001
1986000000
1987000000
1988000000
1989000000
1990000000
1991000000
1992000000
1993000000
1994001001
1995011002
1996010001
1997010001
1998020002
1999010001
2000000000
2001000000
2002000000
2003002002
2004000000
2005011002
2006000000
2007000000
2008000000
2009010001
2010000000
2011000000
2012000000
2013000000
2014000000
2015000000
2016000000
2017000000
Total0990018