*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000101
1970000000
1971000000
1972000101
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981000000
1982000000
1983000000
1984000101
1985000000
1986000000
1987000000
1988000000
1989000101
1990000011
1991000112
1992000101
1993000011
1994000123
1995000112
1996000077
199700011415
1998000000
1999000213
2000000202
2001000314
2002000202
2003000303
2004000202
200500031013
2006000123
2007000224
2008000303
2009000101
2010000415
2011000707
2012000101
2013000022
2014000011
2015000000
2016000022
2017000000
2018000000
Total000454994