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          444        170 
1992          721        293 
1993         1280        477 
1994         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1784        618 
1998        21448       9126 
1999        12863       4957 
2000        37962      15677 
2001        39115      15168 
2002        32453      14302 
2003        56382      23485 
2004        45265      17394 
2005        79815      24594 
2006       102763      33051 
2007       187275      58075 
2008       106024      30474 
2009        88917      25120 
2010       141187      37975 
2011       150072      41683 
2012       140966      39114 
2013       214353      61127 
2014       544902     138691 
2015       795095     209249 
2016       644750     167390 
2017       542747     146933 
2018       337224      94817 
2019       848377     207116 
2020       589964     149629 
2021       800816     189410 
2022       606791     173703 
2023       546612     156422 
2024       605017     173818 
2025       510898     145785