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         1669        610 
1994         2339        844 
1995         4430       1529 
1996         3605       1266 
1997         2337        797 
1998        23345       9841 
1999        14642       5619 
2000        40805      16946 
2001        41903      16352 
2002        33116      14782 
2003        62231      25795 
2004        48878      18758 
2005        87437      26842 
2006       113300      36142 
2007       208312      63743 
2008       129494      36788 
2009       105166      29524 
2010       122275      33908 
2011       184322      50948 
2012       170805      47247 
2013       266699      75619 
2014       664546     169465 
2015       776993     205877 
2016       574736     153879 
2017       562285     153749 
2018       407426     114315 
2019       925345     225968 
2020       715935     183792 
2021      1002183     230319 
2022       691012     197668 
2023       635699     182914 
2024        42679      12291