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         1267        472 
1994         1616        595 
1995         2831        991 
1996         2841       1006 
1997         2852        974 
1998        24565      10330 
1999        13384       5107 
2000        37621      15514 
2001        43190      16996 
2002        40342      16921 
2003        59597      24381 
2004        46670      17812 
2005       311167     139823 
2006       337476     150396 
2007       197250      60980 
2008       114844      32833 
2009        96180      26974 
2010       146215      38967 
2011       154644      42244 
2012       182860      40393 
2013       240791      61087 
2014       538270     132098 
2015       768224     200388 
2016       621632     160456 
2017       535819     145591 
2018       326252      91801 
2019       834683     203865 
2020       563356     142661 
2021       769103     181022 
2022       586986     168142 
2023       534667     153064 
2024       582086     167290 
2025       568642     162352 
2026        53729      14969