*Excludes Observations that spanned multiple years

Pre 19708
19700
19712
197210
19733
197410
19757
19761
19770
19783
19793
198012
198126
198216
198325
198435
198540
198646
198730
198831
198936
199084
199153
199244
199332
199458
199558
199688
199742
199877
199958
200031
2001108
200276
200377
200450
200556
200676
200753
200873
2009102
201085
201190
201267
201355
201433
20152
20167
20172
20180
Total1981