*Excludes Observations that spanned multiple years

  B
b
t
W
w
 
Pre 197000027027
1970001304
1971000606
1972000202
1973000303
1974000202
1975000606
1976000404
1977000303
1978000101
1979000202
1980000404
1981001102
1982000404
1983000101
1984000202
1985000516
1986001416
1987002417
1988003519
1989000202
1990000314
1991001416
1992000516
1993001304
199400312015
199500113014
199600114015
19970027110
19980028111
19990019010
200000410014
200100213116
200200015015
200300118221
200400012113
200500119020
2006001809
200700024024
2008000808
200900420125
201000417021
201100318021
201200015015
201300012012
2014000707
2015000505
2016000303
2017000101
2018000000
Total004039414448