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         1610        593 
1995         2816        986 
1996         2823       1000 
1997         2813        961 
1998        24484      10300 
1999        13329       5087 
2000        37446      15432 
2001        42945      16891 
2002        40109      16817 
2003        59223      24237 
2004        46379      17693 
2005       310451     139570 
2006       336725     150140 
2007       196298      60728 
2008       113823      32559 
2009        94975      26654 
2010       144918      38631 
2011       152626      41700 
2012       180704      39809 
2013       238378      60417 
2014       533086     130783 
2015       763718     199180 
2016       618327     159609 
2017       530521     144190 
2018       322560      90778 
2019       829383     202665 
2020       554391     140483 
2021       757138     178064 
2022       582258     166799 
2023       530649     151932 
2024       576335     165580 
2025       571731     162307 
2026        94315      25136