*Excludes Observations that spanned multiple years

Pre 19700
19700
19710
19720
19731
19740
19750
19760
19771
19780
19792
19800
19810
19820
19831
19843
19853
19862
19873
198826
19890
19906
199180
199242
199364
199413
199538
199610
199725
19983
19991
20000
20012
20021
20030
20049
20052
20061
20071
200817
20096
20100
20112
20121
20131
20140
20150
20163
20177
201815
201917
202018
202127
202242
202336
20247
Total539