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        37960      15676 
2001        39112      15166 
2002        35428      15298 
2003        57871      23982 
2004        45262      17393 
2005        79815      24594 
2006       102763      33051 
2007       187269      58073 
2008       106001      30469 
2009        88917      25120 
2010       141179      37973 
2011       150065      41681 
2012       140946      39109 
2013       214350      61126 
2014       544865     138681 
2015       795911     209474 
2016       644942     167443 
2017       543040     147022 
2018       337237      94820 
2019       848399     207129 
2020       590089     149670 
2021       800769     189397 
2022       606765     173696 
2023       546602     156419 
2024       604533     173699 
2025       512602     146295