*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981000000
1982000000
1983000000
1984000000
1985000000
1986000000
1987000000
1988000000
1989000000
1990000000
1991000000
1992000000
1993000000
1994000000
1995000000
1996000000
1997000000
1998000101
1999000101
2000000101
2001000101
2002000101
2003000000
2004000101
2005000303
2006000303
2007000505
2008000101
2009000101
2010000202
2011000101
2012000000
2013000000
2014000101
2015000000
2016000000
2017000000
2018000000
Total00023023