Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          216         77 
1991          856        306 
1992          664        273 
1993         1213        455 
1994         1549        576 
1995         2558        901 
1996         2770        981 
1997         2659        907 
1998        24183       8635 
1999        12991       4953 
2000        36684      15073 
2001        41753      16403 
2002        35321      15115 
2003        57635      23587 
2004        45388      17278 
2005       305121     137351 
2006       332433     148319 
2007       193400      59844 
2008       110006      31342 
2009        90655      25332 
2010       138782      36945 
2011       146363      39807 
2012       174169      37965 
2013       230062      57988 
2014       482912     119861 
2015       738149     192630 
2016       618793     159765 
2017       518078     140921 
2018       307833      87042 
2019       813016     199239 
2020       535678     135950 
2021       725132     170105 
2022       563635     161594 
2023       516023     147804 
2024       557101     160097 
2025       533340     151159 
2026       272052      59909