*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 1970000000
1970000000
1971000000
1972000000
1973000000
1974000000
1975000000
1976000000
1977001001
1978000000
1979000000
1980000000
1981000000
1982100001
1983010001
1984000000
1985100001
198620130024
198718140023
198854020056
198952050057
199085030088
1991221730042
1992341710052
1993231340040
1994211360040
1995211470042
199632780047
199765750077
199841760054
199968660080
2000509140073
20014010230073
2002428170067
2003622130077
200422170030
200532280042
2006161320031
200723370033
2008191120032
20096070013
201018470029
201112390024
2012422008
20138330014
201412230017
20157340014
201610440018
2017000000
Total941174206001321