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          746        302 
1993         1308        487 
1994         1684        618 
1995         3096       1080 
1996         2980       1053 
1997         1869        645 
1998        22230       9402 
1999        13582       5211 
2000        38756      16025 
2001        39540      15362 
2002        31218      13952 
2003        57970      24120 
2004        46549      17861 
2005        81810      25180 
2006       105437      33834 
2007       192546      59488 
2008       113841      32564 
2009        94099      26512 
2010       120934      33307 
2011       159849      44323 
2012       151119      41868 
2013       223665      63707 
2014       568940     144947 
2015       807278     211604 
2016       664602     172403 
2017       557751     150805 
2018       355027      99720 
2019       870817     212575 
2020       623250     158675 
2021       841375     200028 
2022       627172     179508 
2023       563019     161020 
2024       627351     180658 
2025       172940      49168