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         2277        822 
1995         3362       1169 
1996         3573       1255 
1997         2326        793 
1998        23240       9799 
1999        14514       5565 
2000        40417      16770 
2001        42978      16666 
2002        32428      14495 
2003        61067      25322 
2004        47863      18359 
2005        85036      26146 
2006       110449      35298 
2007       203286      62371 
2008       124548      35456 
2009       101100      28419 
2010       117727      32707 
2011       176201      48730 
2012       163831      45303 
2013       253519      71715 
2014       603545     154538 
2015       728493     193184 
2016       714658     184630 
2017       600075     161941 
2018       394950     110673 
2019       929724     228308 
2020       682175     174706 
2021       891984     213457 
2022       662422     189456 
2023       600590     172930 
2024       260643      75545