*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19730
19740
19750
19760
19770
19780
19790
19801
19810
19820
19830
19840
19852
19860
19874
198818
198918
19909
19917
199216
19935
19946
19953
19960
199721
19987
19992
20003
20018
20020
200312
20043
20055
200611
20072
200810
20091
20100
20110
20120
20130
20140
20150
20161
20170
Total175