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*Excludes Observations that spanned multiple years

Pre 19700
19700
19711
197217
19732
19740
19750
19760
19770
19780
19790
19800
19810
19820
19831
198411
19853
198617
198779
1988121
198952
199059
199192
199272
199393
199414
199575
199639
199741
19988
199938
200019
200122
20027
20033
20044
20052
20060
20071
20081
20090
20106
201110
20129
201331
201411
20156
20168
20172
20182
20190
20201
20210
Total980