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         2845        996 
1996         2850       1009 
1997         2870        980 
1998        24586      10336 
1999        13438       5126 
2000        37707      15551 
2001        43237      17015 
2002        40421      16951 
2003        60094      24559 
2004        46847      17877 
2005       311929     140138 
2006       338029     150597 
2007       197945      61177 
2008       115436      32992 
2009        96765      27131 
2010       147221      39214 
2011       156035      42614 
2012       184145      40744 
2013       242177      61476 
2014       542978     133282 
2015       778751     202893 
2016       625027     161295 
2017       540234     146749 
2018       329168      92588 
2019       838299     204836 
2020       570796     144548 
2021       780374     183870 
2022       590985     169255 
2023       537497     153822 
2024       587823     168932 
2025       604621     172789 
2026        50506      14001