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          444        170 
1992          724        294 
1993         1283        478 
1994         1640        603 
1995         2912       1018 
1996         2898       1025 
1997         1793        621 
1998        21472       9137 
1999        12936       4983 
2000        38079      15730 
2001        39757      15395 
2002        31815      14097 
2003        56565      23571 
2004        45495      17477 
2005        80095      24681 
2006       103167      33171 
2007       188317      58356 
2008       107403      30849 
2009        90045      25420 
2010       141905      38163 
2011       151753      42139 
2012       142921      39646 
2013       215704      61509 
2014       550305     140118 
2015       794217     208937 
2016       648210     168328 
2017       545193     147562 
2018       340183      95628 
2019       851735     207847 
2020       596290     151377 
2021       806871     191044 
2022       609320     174443 
2023       549662     157304 
2024       605792     174164 
2025       478257     136707