*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970200002
1970000000
1971000000
1972000000
1973000000
1974100001
1975000000
1976000101
1977000000
1978000000
1979000101
1980000000
1981100001
1982000000
1983000000
1984000000
1985000000
1986000000
1987100203
1988000202
1989000101
1990000202
1991000404
1992000505
1993000101
1994000303
199500012012
1996000505
1997100203
1998000101
1999000101
2000000505
2001000707
2002000808
2003000202
2004000606
2005000101
2006100203
2007100304
2008100405
2009000707
2010000606
2011000505
2012000202
2013000000
2014000000
2015000000
2016000202
2017000000
2018000000
Total9001030112