Year Observations     Objects
1858            3          3 
1889            1          1 
1901            1          1 
1920            6          2 
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          228         81 
1991          867        310 
1992          716        291 
1993         1264        471 
1994         1616        595 
1995         2825        989 
1996         2832       1003 
1997         2828        966 
1998        24504      10308 
1999        13346       5093 
2000        37508      15459 
2001        43030      16923 
2002        40204      16856 
2003        59356      24280 
2004        46469      17729 
2005       310575     139615 
2006       336884     150194 
2007       196508      60782 
2008       114034      32615 
2009        95263      26728 
2010       145217      38708 
2011       153000      41798 
2012       181223      39945 
2013       238809      60533 
2014       533967     131001 
2015       764493     199405 
2016       618334     159609 
2017       531101     144344 
2018       323237      90966 
2019       829587     202698 
2020       555575     140722 
2021       758979     178522 
2022       583003     167011 
2023       531243     152099 
2024       577062     165822 
2025       568017     162393 
2026        90889      24165