*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19811
19820
19830
19840
19850
19860
19873
19883
19893
19900
19915
199210
19935
19947
199545
19961
19974
199829
19996
20007
20015
20021
200314
200418
200531
20066
200715
200820
200912
201051
201165
201229
201325
201441
201530
201628
201719
20180
Total539