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         4430       1529 
1996         3605       1266 
1997         2337        797 
1998        23345       9841 
1999        14644       5620 
2000        40811      16949 
2001        41914      16356 
2002        33128      14787 
2003        62249      25803 
2004        48885      18761 
2005        87498      26859 
2006       113352      36157 
2007       208411      63770 
2008       129584      36813 
2009       105233      29542 
2010       122341      33925 
2011       184478      50990 
2012       170933      47281 
2013       266922      75681 
2014       665172     169616 
2015       777693     206055 
2016       574863     153915 
2017       558673     153089 
2018       407568     114367 
2019       924987     225897 
2020       716540     183956 
2021      1002878     230507 
2022       691787     197882 
2023       637405     183402 
2024        24330       7236