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          492        186 
1992          770        310 
1993         1356        504 
1994         1752        642 
1995         3315       1153 
1996         3407       1198 
1997         2291        783 
1998        23133       9758 
1999        14444       5537 
2000        40051      16608 
2001        40905      15936 
2002        32600      14517 
2003        60059      24939 
2004        47424      18194 
2005        83376      25651 
2006       107672      34488 
2007       197853      60915 
2008       119347      34045 
2009        98032      27592 
2010       113064      31487 
2011       167422      46365 
2012       157804      43692 
2013       234927      66827 
2014       577266     147292 
2015       698120     184257 
2016       673590     174417 
2017       575195     155343 
2018       372158     104421 
2019       897333     219368 
2020       648595     165434 
2021       867553     206832 
2022       642869     184057 
2023       586837     167989 
2024       456529     132996