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         2851        998 
1996         2865       1014 
1997         2870        980 
1998        24600      10341 
1999        13446       5129 
2000        37738      15565 
2001        43260      17027 
2002        40468      16970 
2003        60214      24611 
2004        46939      17911 
2005       312156     140205 
2006       338299     150705 
2007       198189      61246 
2008       115793      33088 
2009        97197      27245 
2010       147484      39282 
2011       156662      42783 
2012       184732      40901 
2013       243001      61698 
2014       547282     134349 
2015       789596     204974 
2016       626047     161532 
2017       541996     147135 
2018       330297      92900 
2019       840967     205481 
2020       574559     145580 
2021       785472     185295 
2022       596418     170766 
2023       539869     154473 
2024       591507     169981 
2025       613511     175239 
2026         7414       2178