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          492        186 
1992          770        310 
1993         1356        504 
1994         2249        812 
1995         3359       1168 
1996         3570       1254 
1997         2326        793 
1998        23228       9795 
1999        14503       5561 
2000        40381      16754 
2001        42882      16627 
2002        32398      14482 
2003        60906      25261 
2004        47786      18330 
2005        84601      26019 
2006       109811      35110 
2007       202211      62078 
2008       123418      35145 
2009       100189      28174 
2010       116595      32413 
2011       173933      48123 
2012       161615      44727 
2013       247308      70200 
2014       596164     152794 
2015       722090     191556 
2016       707907     183178 
2017       597256     161284 
2018       392365     109957 
2019       925948     227367 
2020       677088     173385 
2021       888973     212620 
2022       660643     188939 
2023       612785     173649 
2024       269433      78108