*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
197214
19732
19740
19750
19760
19770
19780
19790
19800
19810
19821
19831
198416
198555
198641
198754
198858
198923
199052
199144
19929
199353
199412
199552
199620
199718
19981
199946
200046
200117
20027
20033
20040
20051
20061
20073
20085
20094
20101
20113
20121
20132
20143
20153
20167
20172
20181
20190
20200
Total682