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         1267        472 
1994         1616        595 
1995         2840        994 
1996         2847       1008 
1997         2861        977 
1998        24577      10333 
1999        13417       5119 
2000        37673      15538 
2001        43223      17011 
2002        40408      16947 
2003        60034      24536 
2004        46814      17866 
2005       311652     140009 
2006       337947     150566 
2007       197873      61158 
2008       115331      32965 
2009        96630      27094 
2010       147161      39198 
2011       155898      42577 
2012       183958      40698 
2013       241927      61404 
2014       541377     132916 
2015       771740     201338 
2016       623987     161061 
2017       539583     146606 
2018       328726      92472 
2019       838080     204784 
2020       569393     144223 
2021       779101     183546 
2022       589755     168914 
2023       536861     153646 
2024       586949     168684 
2025       603379     172464 
2026        52037      14509