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         1273        474 
1994         1616        595 
1995         2845        996 
1996         2850       1009 
1997         2870        980 
1998        24586      10336 
1999        13438       5126 
2000        37710      15552 
2001        43240      17016 
2002        40425      16953 
2003        60109      24565 
2004        46849      17878 
2005       311951     140147 
2006       338097     150626 
2007       197975      61185 
2008       115469      33000 
2009        96802      27142 
2010       147258      39224 
2011       156195      42657 
2012       184213      40762 
2013       242439      61546 
2014       543256     133356 
2015       779320     203035 
2016       625225     161339 
2017       540788     146893 
2018       329391      92647 
2019       839090     205042 
2020       573159     145197 
2021       783268     184678 
2022       594062     170103 
2023       538876     154196 
2024       589271     169336 
2025       605924     173146 
2026        50509      13967