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          465        177 
1992          730        296 
1993         1283        478 
1994         1643        604 
1995         2921       1021 
1996         2916       1031 
1997         1801        624 
1998        21487       9142 
1999        12959       4991 
2000        38129      15754 
2001        40148      15529 
2002        32118      14202 
2003        56759      23647 
2004        45567      17504 
2005        80249      24726 
2006       103316      33214 
2007       188773      58478 
2008       108189      31060 
2009        90442      25526 
2010       142271      38256 
2011       152479      42339 
2012       143794      39886 
2013       216254      61668 
2014       552676     140751 
2015       792857     208541 
2016       649500     168689 
2017       546149     147814 
2018       341731      96060 
2019       852321     207942 
2020       599310     152223 
2021       809520     191768 
2022       610578     174797 
2023       550746     157614 
2024       609772     175125 
2025       480764     137030