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        22230       9402 
1999        13582       5211 
2000        38758      16026 
2001        39540      15362 
2002        31226      13955 
2003        57982      24125 
2004        46551      17862 
2005        81810      25180 
2006       105444      33836 
2007       192583      59498 
2008       113914      32583 
2009        94128      26520 
2010       120971      33317 
2011       159926      44344 
2012       151184      41886 
2013       223690      63714 
2014       569016     144967 
2015       806710     211441 
2016       664681     172424 
2017       557822     150826 
2018       355140      99751 
2019       870993     212615 
2020       623356     158704 
2021       841521     200070 
2022       627293     179542 
2023       563116     161047 
2024       627380     180666 
2025       171131      48712