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          477        181 
1992          755        305 
1993         1334        496 
1994         1703        625 
1995         3156       1100 
1996         3022       1068 
1997         2006        691 
1998        22525       9506 
1999        13796       5287 
2000        39141      16198 
2001        39903      15516 
2002        31325      14031 
2003        58635      24387 
2004        46994      18033 
2005        82596      25415 
2006       106361      34105 
2007       194506      60019 
2008       116431      33252 
2009        95954      27022 
2010       110649      30861 
2011       163276      45254 
2012       154496      42794 
2013       227495      64774 
2014       558737     142847 
2015       770486     202264 
2016       664146     172288 
2017       564794     152681 
2018       362221     101704 
2019       880935     215139 
2020       633900     161491 
2021       854518     203449 
2022       635691     181971 
2023       572004     163775 
2024       642460     185020 
2025        51518      14768