Year Observations
2023         6797
2022       426913
2021       416191
2020       387417
2019       452676
2018       422346
2017       399746
2016       400093
2015       394132
2014       259481
2013       249525
2012       243082
2011       187643
2010       188174
2009       168668
2008       171941
2007       142054
2006       143571
2005       142000
2004       166269
2003       155299
2002       123100
2001        80733
2000        63583
1999        32019
1998        20176
1997         7183
1996         3259
1995         1890
1994         1485
1993          470