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         2552        899 
1996         2770        981 
1997         2656        906 
1998        24179       8633 
1999        12986       4951 
2000        36670      15066 
2001        41740      16397 
2002        35299      15105 
2003        57606      23573 
2004        45363      17268 
2005       305044     137321 
2006       332345     148282 
2007       193333      59826 
2008       109970      31333 
2009        90589      25315 
2010       138704      36925 
2011       146281      39786 
2012       174101      37947 
2013       229917      57948 
2014       482617     119788 
2015       730400     190873 
2016       612393     158337 
2017       517828     140852 
2018       307601      86978 
2019       812482     199109 
2020       534973     135749 
2021       724368     169944 
2022       563246     161482 
2023       515783     147738 
2024       556742     160007 
2025       532680     150999 
2026       271007      59617