*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977001001
1978000000
1979000000
1980000000
1981001001
1982000000
1983000000
1984000000
1985001001
1986002002
1987004004
1988003003
1989003003
1990002002
1991008008
1992006006
1993008008
1994007007
1995009009
1996008008
1997008008
199800160016
1999008008
200000140014
200100250025
200200300030
200300220022
200400110011
2005009009
200600140014
200700230023
200800150015
200900140014
201000110011
201100180018
2012005005
2013004004
2014002002
2015004004
2016000000
2017001001
Total0031700317