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         2831        967 
1998        24516      10312 
1999        13353       5096 
2000        37534      15471 
2001        43056      16935 
2002        40222      16864 
2003        59402      24300 
2004        46485      17735 
2005       310711     139658 
2006       337018     150238 
2007       196629      60815 
2008       114263      32675 
2009        95491      26789 
2010       145474      38776 
2011       153339      41889 
2012       181575      40041 
2013       239245      60653 
2014       534590     131151 
2015       765334     199634 
2016       618833     159731 
2017       532340     144647 
2018       323823      91127 
2019       830348     202870 
2020       556896     141077 
2021       761100     179040 
2022       584086     167315 
2023       531961     152301 
2024       578202     166154 
2025       570308     162887 
2026        65575      18415