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        37444      15431 
2001        42942      16890 
2002        40104      16815 
2003        59221      24236 
2004        46370      17690 
2005       310447     139569 
2006       336725     150140 
2007       196294      60727 
2008       113797      32552 
2009        94967      26651 
2010       144915      38630 
2011       152630      41701 
2012       180673      39800 
2013       238375      60416 
2014       533081     130781 
2015       763734     199182 
2016       618303     159604 
2017       530625     144228 
2018       322516      90767 
2019       829433     202680 
2020       554375     140478 
2021       757085     178051 
2022       582211     166787 
2023       530625     151926 
2024       576287     165565 
2025       571718     162303 
2026        94857      25302