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        13320       5084 
2000        37442      15430 
2001        42936      16887 
2002        40104      16815 
2003        59215      24235 
2004        46367      17689 
2005       310433     139565 
2006       336721     150138 
2007       196256      60717 
2008       113785      32549 
2009        94951      26647 
2010       144903      38627 
2011       152602      41694 
2012       180646      39793 
2013       238333      60406 
2014       533075     130778 
2015       764184     199298 
2016       618316     159610 
2017       530830     144288 
2018       322531      90772 
2019       829827     202801 
2020       554332     140467 
2021       756970     178018 
2022       582158     166772 
2023       530611     151922 
2024       576163     165551 
2025       571115     162298 
2026        99481      26495