*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 197011011013
1970200002
1971300003
1972000000
1973200002
1974000101
1975200002
1976300003
1977500106
1978100001
1979000000
1980200002
1981500005
1982200024
1983300104
1984300104
1985500106
19868015014
19874006111
1988120010022
19895104010
1990000505
19916005011
199210008321
199310008119
199412009829
19957018622
199680026337
199713009022
19986009217
199917002221
20009005014
20017000310
2002200507
20035013211
200470017529
2005110010223
200610107018
2007170010229
200810205118
20093026011
201010117423
201150016021
201291212024
20138117017
20140002911
20152008010
2016300115
2017200103
2018000000
Total27861025257603