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         2900       1014 
1996         2895       1024 
1997         1787        619 
1998        21450       9127 
1999        12875       4962 
2000        37994      15692 
2001        39329      15245 
2002        32982      14479 
2003        56267      23454 
2004        45346      17423 
2005        79862      24609 
2006       102834      33073 
2007       187455      58122 
2008       106364      30566 
2009        89209      25195 
2010       141358      38020 
2011       150524      41804 
2012       141515      39264 
2013       214676      61216 
2014       545998     138992 
2015       794643     209121 
2016       644950     167459 
2017       543651     147149 
2018       338009      95037 
2019       849432     207392 
2020       591563     150060 
2021       802207     189769 
2022       607694     173965 
2023       547381     156652 
2024       606879     174163 
2025       546619     156774