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          231         82 
1991          867        310 
1992          721        293 
1993         1280        477 
1994         1628        599 
1995         2881       1008 
1996         2886       1021 
1997         2927        999 
1998        24680      10372 
1999        13483       5143 
2000        37900      15637 
2001        43387      17083 
2002        40638      17044 
2003        60509      24725 
2004        47177      17996 
2005       312885     140508 
2006       339203     151091 
2007       198811      61415 
2008       116925      33398 
2009        97818      27408 
2010       148213      39446 
2011       157891      43118 
2012       186130      41286 
2013       244759      62176 
2014       562809     137917 
2015       812600     210253 
2016       634019     163529 
2017       546033     147884 
2018       333322      93698 
2019       845168     206518 
2020       582812     147640 
2021       793626     187534 
2022       601622     172236 
2023       543089     155406 
2024       599465     172242 
2025       587444     167819