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          719        292 
1993         1273        474 
1994         1625        598 
1995         2848        997 
1996         2865       1014 
1997         2870        980 
1998        24598      10340 
1999        13441       5127 
2000        37734      15563 
2001        43254      17024 
2002        40462      16967 
2003        60199      24604 
2004        46908      17900 
2005       312107     140185 
2006       338275     150698 
2007       198148      61235 
2008       115745      33075 
2009        97135      27229 
2010       147433      39268 
2011       156575      42759 
2012       184662      40881 
2013       242927      61678 
2014       545313     133840 
2015       784594     204148 
2016       625787     161467 
2017       541781     147101 
2018       330119      92851 
2019       840810     205436 
2020       574277     145499 
2021       785057     185175 
2022       595777     170586 
2023       539565     154383 
2024       590979     169830 
2025       612902     175061 
2026        10930       3225