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          740        300 
1993         1296        483 
1994         1661        610 
1995         2994       1046 
1996         2953       1044 
1997         1822        631 
1998        21587       9186 
1999        13144       5056 
2000        38427      15884 
2001        39252      15246 
2002        31561      14042 
2003        57470      23922 
2004        46097      17695 
2005        80848      24905 
2006       104303      33507 
2007       190843      59033 
2008       111157      31854 
2009        92188      25999 
2010       144323      38787 
2011       156105      43325 
2012       147520      40894 
2013       219109      62458 
2014       562819     143448 
2015       798547     210129 
2016       656136     170507 
2017       552038     149468 
2018       349232      98134 
2019       860676     210106 
2020       613505     156121 
2021       824953     195831 
2022       617058     176638 
2023       556167     159112 
2024       612867     176560 
2025       287001      82584