*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 19700011810
1970000000
1971000000
1972000022
1973000011
1974000011
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981000000
1982000000
1983000000
1984000000
1985000000
1986000101
1987000000
1988000000
1989000101
1990000000
1991000000
1992000000
1993000000
1994000000
1995000000
1996000000
1997000000
1998000000
1999000134
2000000011
2001000011
2002000213
2003000101
2004000000
2005000101
200600083038
2007000000
2008000000
2009000000
2010000235
2011000202
2012000000
2013000101
2014000011
2015000000
2016000202
2017000101
2018000000
Total001245277