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         1270        473 
1994         1616        595 
1995         2845        996 
1996         2850       1009 
1997         2870        980 
1998        24586      10336 
1999        13438       5126 
2000        37707      15551 
2001        43240      17016 
2002        40423      16952 
2003        60102      24562 
2004        46849      17878 
2005       311947     140146 
2006       338088     150623 
2007       197960      61181 
2008       115450      32996 
2009        96795      27140 
2010       147247      39221 
2011       156135      42641 
2012       184186      40755 
2013       242287      61506 
2014       543156     133329 
2015       779301     203031 
2016       625283     161347 
2017       540661     146858 
2018       329371      92641 
2019       838791     204962 
2020       571777     144819 
2021       781790     184268 
2022       592645     169715 
2023       538392     154064 
2024       588706     169177 
2025       605123     172928 
2026        50492      13964