*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
1972100
197343
19740
19751
19760
19770
19780
19790
19801
19810
19820
19832
198447
198536
198641
1987126
1988254
198965
1990134
1991311
1992248
199362
19948
19952
19960
19970
19983
1999138
2000128
200197
200219
20034
200441
20051
20062
20073
200817
200914
201016
201120
20124
20135
201410
20158
201622
20179
20189
20190
Total2051