*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 197013000013
1970100001
1971200002
1972200002
1973100001
1974000000
1975000000
1976100001
1977000000
1978200002
1979100001
1980000000
1981200103
1982000101
1983300306
1984200002
1985300003
1986200204
1987200103
1988200002
1989700007
1990210003
1991110406
1992400206
1993500106
1994110103
1995200103
1996100102
1997100203
1998600107
1999000000
2000400105
2001200305
2002200406
2003000404
2004300003
2005500207
2006100203
2007000101
20085104010
2009400105
2010200002
201160014020
2012400105
2013000000
2014000000
2015000000
2016000000
2017000000
2018000000
Total10740580169