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          735        298 
1993         1283        478 
1994         1655        608 
1995         2948       1030 
1996         2944       1041 
1997         1813        628 
1998        21556       9172 
1999        13067       5029 
2000        38243      15803 
2001        39151      15203 
2002        30593      13707 
2003        57173      23807 
2004        45861      17606 
2005        80554      24816 
2006       103883      33382 
2007       190018      58811 
2008       109988      31540 
2009        91485      25807 
2010       143288      38524 
2011       154441      42870 
2012       145832      40438 
2013       217658      62052 
2014       558470     142310 
2015       797854     209858 
2016       654790     170113 
2017       549652     148781 
2018       345733      97165 
2019       858230     209415 
2020       607448     154476 
2021       817418     193896 
2022       613766     175703 
2023       553491     158367 
2024       608270     175140 
2025       364007     104690