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          465        177 
1992          732        297 
1993         1283        478 
1994         1643        604 
1995         2930       1024 
1996         2933       1037 
1997         1801        624 
1998        21524       9158 
1999        12987       5001 
2000        38167      15772 
2001        39053      15165 
2002        30829      13780 
2003        56958      23723 
2004        45738      17566 
2005        80411      24773 
2006       103596      33297 
2007       189407      58645 
2008       108981      31269 
2009        90970      25667 
2010       142724      38374 
2011       153393      42581 
2012       144833      40164 
2013       216908      61849 
2014       555366     141463 
2015       795296     209174 
2016       651916     169330 
2017       547784     148266 
2018       343510      96554 
2019       855548     208747 
2020       603110     153258 
2021       813245     192766 
2022       612201     175259 
2023       552136     158001 
2024       606430     174577 
2025       432689     123510