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          767        309 
1993         1356        504 
1994         1746        640 
1995         3291       1145 
1996         3243       1142 
1997         2288        782 
1998        23088       9741 
1999        14416       5526 
2000        39970      16572 
2001        40784      15887 
2002        32305      14408 
2003        59790      24834 
2004        47307      18151 
2005        83050      25552 
2006       107080      34315 
2007       196391      60521 
2008       118006      33678 
2009        97274      27384 
2010       111846      31171 
2011       165581      45876 
2012       156581      43359 
2013       231160      65794 
2014       575068     146666 
2015       750465     196358 
2016       669658     173396 
2017       571084     154258 
2018       367762     103202 
2019       890446     217527 
2020       642883     163874 
2021       862816     205560 
2022       639840     183144 
2023       579208     165831 
2024       511440     147854