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         1619        596 
1995         2848        997 
1996         2865       1014 
1997         2870        980 
1998        24595      10339 
1999        13441       5127 
2000        37730      15561 
2001        43250      17021 
2002        40454      16965 
2003        60129      24573 
2004        46893      17894 
2005       312029     140174 
2006       338177     150656 
2007       198106      61222 
2008       115648      33050 
2009        97007      27199 
2010       147388      39258 
2011       156450      42728 
2012       184559      40855 
2013       242792      61643 
2014       544897     133736 
2015       783154     203870 
2016       625320     161346 
2017       541708     147099 
2018       329934      92799 
2019       840618     205392 
2020       574020     145429 
2021       784637     185059 
2022       595335     170462 
2023       539402     154339 
2024       590612     169723 
2025       609966     174293 
2026        22190       6330