*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19800
19810
19820
19830
19840
19850
19860
19874
198813
19890
19902
19911
19922
19936
19944
199526
199621
199736
199815
19993
20005
20012
20022
200310
20043
20051
20062
20072
20080
20090
20100
20110
20120
20130
20140
20150
20160
20170
Total160