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          532        200 
1992          936        367 
1993         1672        611 
1994         2339        844 
1995         4433       1530 
1996         3605       1266 
1997         2337        797 
1998        23345       9841 
1999        14646       5620 
2000        40847      16964 
2001        41932      16364 
2002        33178      14807 
2003        62281      25815 
2004        48914      18772 
2005        87615      26892 
2006       113447      36186 
2007       208562      63812 
2008       129848      36884 
2009       105486      29612 
2010       122507      33969 
2011       185008      51134 
2012       171224      47361 
2013       267665      75887 
2014       666284     169900 
2015       778668     206322 
2016       574784     153873 
2017       550509     151471 
2018       407893     114455 
2019       923669     225584 
2020       717733     184262 
2021      1067833     250954 
2022       693168     198300 
2023       642000     184739 
2024        15306       4760