*Excludes Observations that spanned multiple years

Pre 197071
1970181
1971163
1972195
197352
197493
1975105
197653
197774
197893
197924
198035
1981124
198242
198329
198471
198540
198617
19875
1988152
1989168
1990157
1991161
1992133
1993639
1994355
1995306
1996182
1997145
1998115
1999203
2000330
2001225
2002222
2003104
200431
2005100
2006178
2007263
2008157
2009103
2010111
2011109
201292
2013127
201425
201521
201621
20172
Total6404