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         1283        478 
1994         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1787        619 
1998        21450       9127 
1999        12872       4961 
2000        37986      15688 
2001        39314      15238 
2002        32441      14296 
2003        56234      23440 
2004        45331      17418 
2005        79831      24599 
2006       102809      33066 
2007       187394      58106 
2008       106250      30536 
2009        89146      25182 
2010       141293      38003 
2011       150398      41770 
2012       141373      39226 
2013       214572      61186 
2014       545622     138890 
2015       794815     209168 
2016       644731     167398 
2017       543396     147078 
2018       337796      94975 
2019       849011     207290 
2020       590810     149866 
2021       801737     189636 
2022       607367     173865 
2023       546898     156501 
2024       605301     173900 
2025       508932     145107