*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19794
19800
19810
19824
19831
19840
19850
19863
19872
19882
19890
19906
19914
19920
19939
199418
19956
19966
19973
19980
19991
200015
20015
20023
20037
20046
20055
20065
20073
20082
20091
20100
20113
20120
20130
20140
20150
20160
20170
20180
Total124