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         2983       1054 
1997         1872        646 
1998        22289       9422 
1999        13584       5212 
2000        38754      16026 
2001        39545      15364 
2002        42471      17704 
2003        57991      24128 
2004        46558      17864 
2005        81838      25189 
2006       105485      33848 
2007       192659      59518 
2008       114009      32608 
2009        94158      26529 
2010       121005      33326 
2011       160019      44370 
2012       151250      41904 
2013       223753      63732 
2014       569135     145000 
2015       803625     210596 
2016       664912     172484 
2017       557965     150867 
2018       355324      99799 
2019       870931     212608 
2020       623500     158749 
2021       841860     200152 
2022       627560     179619 
2023       563290     161095 
2024       627613     180727 
2025       169402      48281