*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977000000
1978000000
1979000000
1980000000
1981000000
1982000000
1983000000
1984000000
1985000000
1986000000
1987001001
1988002002
1989101002
1990101002
1991123006
1992012003
1993125008
1994004004
1995008008
1996002002
1997003003
1998011002
1999006006
2000006006
200101100011
200200110011
200312100013
2004024006
2005007007
200600110011
200700130013
200800110011
200900120012
201010160017
201100220022
2012001001
2013013004
2014000000
2015000000
2016001001
2017000000
Total61217700195