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         2268        819 
1995         3362       1169 
1996         3573       1255 
1997         2326        793 
1998        23240       9799 
1999        14511       5564 
2000        40413      16768 
2001        42973      16664 
2002        32428      14495 
2003        61059      25319 
2004        47861      18358 
2005        84994      26134 
2006       110431      35293 
2007       203254      62362 
2008       124516      35447 
2009       101068      28410 
2010       117663      32691 
2011       176114      48706 
2012       163782      45290 
2013       253373      71676 
2014       603343     154484 
2015       728227     193110 
2016       713821     184457 
2017       599808     161897 
2018       394785     110631 
2019       929669     228291 
2020       681985     174652 
2021       891903     213434 
2022       662312     189425 
2023       600389     172874 
2024       259280      75150