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         2921       1021 
1996         2916       1031 
1997         1801        624 
1998        21490       9143 
1999        12962       4992 
2000        38129      15754 
2001        40163      15534 
2002        32137      14209 
2003        56773      23652 
2004        45570      17505 
2005        80256      24728 
2006       103325      33217 
2007       188789      58482 
2008       108218      31068 
2009        90442      25526 
2010       142275      38257 
2011       152487      42341 
2012       143822      39893 
2013       216266      61671 
2014       552694     140756 
2015       792810     208528 
2016       649545     168699 
2017       546156     147816 
2018       341760      96069 
2019       852358     207953 
2020       599361     152237 
2021       809558     191779 
2022       610601     174804 
2023       550789     157626 
2024       609872     175150 
2025       466205     132952