*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979100001
1980000000
1981000000
1982000000
1983000000
1984000000
1985000000
1986003003
1987003003
1988004004
1989000000
1990002002
1991012003
1992003003
1993002002
1994001001
1995001001
199600110011
1997002002
1998000000
1999102003
2000000000
2001000000
200200120012
2003002002
2004001001
2005000000
2006003003
2007002002
2008001001
2009001001
2010000000
2011000000
2012000000
2013000000
2014000000
2015000000
2016000000
2017000000
Total21580061