*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19781
19790
19800
19810
19820
19836
19841
19851
19862
19875
198839
19896
199021
199121
199225
199326
199413
199530
19967
199724
199833
19999
20007
20019
20022
200323
20047
200513
200610
20077
200812
200914
201011
201112
20127
20138
20148
20158
201623
201715
20180
Total466