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          503        190 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         3799       1316 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14542       5577 
2000        40522      16817 
2001        43119      16724 
2002        32594      14571 
2003        61413      25458 
2004        48151      18469 
2005        85846      26384 
2006       111272      35545 
2007       205088      62856 
2008       126176      35894 
2009       102683      28846 
2010       119237      33103 
2011       179040      49511 
2012       166192      45987 
2013       258177      73085 
2014       648228     163977 
2015       744474     197551 
2016       573134     152937 
2017       611349     163933 
2018       404410     113359 
2019       941939     230472 
2020       694237     178063 
2021       901491     215920 
2022       669307     191429 
2023       610117     175610 
2024       200739      57740