Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          492        186 
1992          770        310 
1993         1477        545 
1994         2317        836 
1995         3365       1170 
1996         3576       1256 
1997         2326        793 
1998        23250       9803 
1999        14520       5567 
2000        40436      16778 
2001        42993      16672 
2002        32451      14505 
2003        61101      25334 
2004        47903      18372 
2005        85122      26172 
2006       110573      35336 
2007       203483      62424 
2008       124706      35500 
2009       101280      28468 
2010       117869      32746 
2011       176513      48814 
2012       164014      45352 
2013       254132      71884 
2014       604188     154693 
2015       729284     193397 
2016       714791     184645 
2017       600708     162065 
2018       395433     110805 
2019       929016     228089 
2020       683198     175002 
2021       892617     213642 
2022       662720     189547 
2023       601468     173179 
2024       244949      70929