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          471        179 
1992          749        303 
1993         1310        488 
1994         1692        621 
1995         3111       1085 
1996         3002       1061 
1997         1925        664 
1998        22341       9441 
1999        13620       5227 
2000        38900      16091 
2001        39666      15417 
2002        31083      13927 
2003        58283      24244 
2004        46813      17966 
2005        82260      25312 
2006       105972      33991 
2007       193747      59812 
2008       115500      33000 
2009        95184      26811 
2010       114361      31744 
2011       161943      44894 
2012       153233      42448 
2013       225953      64346 
2014       568972     145040 
2015       793858     207935 
2016       664801     172436 
2017       561098     151761 
2018       359231     100880 
2019       876597     214053 
2020       629641     160383 
2021       849403     202167 
2022       632733     181117 
2023       571210     163219 
2024       635735     183052 
2025       114390      32194