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          468        178 
1992          737        299 
1993         1288        480 
1994         1655        608 
1995         2973       1039 
1996         2953       1044 
1997         1815        629 
1998        21580       9183 
1999        13088       5037 
2000        38341      15845 
2001        39209      15226 
2002        30726      13756 
2003        57340      23870 
2004        46003      17660 
2005        80683      24856 
2006       104114      33450 
2007       190445      58926 
2008       110637      31715 
2009        91910      25921 
2010       143817      38658 
2011       155285      43103 
2012       146845      40715 
2013       218326      62237 
2014       561108     143021 
2015       799321     210273 
2016       656173     170490 
2017       550958     149147 
2018       347622      97686 
2019       859530     209792 
2020       610981     155424 
2021       821687     195014 
2022       615462     176185 
2023       554605     158673 
2024       609953     175743 
2025       316561      90482