*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000011
1973000000
1974000011
1975000011
1976000011
1977000011
1978000011
1979000011
1980000011
1981100012
1982000011
1983000011
1984000011
1985000011
1986000011
1987000011
1988000011
1989000011
1990000011
1991100001
1992000000
1993000011
1994001012
1995000011
1996000000
1997000000
1998000000
1999000000
2000000000
2001000000
2002000000
2003000000
2004000000
2005000000
2006000000
2007000000
2008000000
2009000000
2010000000
2011000000
2012000000
2013005005
2014000000
2015000000
2016000000
2017000000
Total20602129