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          471        179 
1992          749        303 
1993         1308        487 
1994         1686        619 
1995         3108       1084 
1996         2989       1056 
1997         1902        656 
1998        22340       9440 
1999        13611       5224 
2000        38835      16061 
2001        39613      15394 
2002        31016      13895 
2003        58177      24201 
2004        46692      17917 
2005        82066      25254 
2006       105746      33924 
2007       193280      59687 
2008       114980      32862 
2009        94761      26696 
2010       114007      31653 
2011       161225      44699 
2012       152508      42249 
2013       225013      64086 
2014       569249     145073 
2015       799202     209282 
2016       664193     172255 
2017       559806     151394 
2018       357675     100449 
2019       874446     213517 
2020       627500     159783 
2021       846843     201497 
2022       630999     180617 
2023       567515     162296 
2024       632587     182140 
2025       125190      35668