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          465        177 
1992          730        296 
1993         1283        478 
1994         1643        604 
1995         2924       1022 
1996         2921       1033 
1997         1801        624 
1998        21502       9148 
1999        12972       4996 
2000        38139      15759 
2001        39203      15212 
2002        32382      14294 
2003        56881      23692 
2004        45669      17541 
2005        80318      24746 
2006       103518      33273 
2007       189160      58580 
2008       108718      31200 
2009        90767      25612 
2010       142557      38331 
2011       153031      42483 
2012       144406      40048 
2013       216684      61787 
2014       554389     141209 
2015       794184     208885 
2016       650938     169067 
2017       547208     148104 
2018       342814      96362 
2019       854597     208488 
2020       601659     152883 
2021       811790     192369 
2022       611535     175070 
2023       551685     157875 
2024       612931     175889 
2025       439705     124468