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         1666        612 
1995         3015       1053 
1996         2962       1047 
1997         1828        633 
1998        21610       9194 
1999        13274       5101 
2000        38529      15928 
2001        39318      15273 
2002        33181      14591 
2003        57620      23983 
2004        46204      17735 
2005        81098      24978 
2006       104641      33607 
2007       191332      59165 
2008       111841      32036 
2009        92613      26116 
2010       145002      38957 
2011       157113      43599 
2012       148460      41148 
2013       220268      62773 
2014       564997     143970 
2015       798253     210151 
2016       657961     170998 
2017       554305     150048 
2018       350792      98559 
2019       862871     210647 
2020       616211     156833 
2021       829053     196852 
2022       619136     177234 
2023       558225     159694 
2024       617041     177815 
2025       220153      62922