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         2843        995 
1996         2850       1009 
1997         2870        980 
1998        24583      10335 
1999        13438       5126 
2000        37695      15547 
2001        43234      17014 
2002        40421      16951 
2003        60078      24553 
2004        46833      17872 
2005       311915     140133 
2006       338022     150595 
2007       197923      61171 
2008       115422      32988 
2009        96692      27111 
2010       147199      39208 
2011       155995      42603 
2012       184100      40732 
2013       242091      61451 
2014       542922     133268 
2015       778594     202860 
2016       625052     161308 
2017       539987     146696 
2018       329081      92563 
2019       838386     204863 
2020       570669     144512 
2021       780216     183829 
2022       590852     169217 
2023       537420     153801 
2024       587614     168871 
2025       604327     172705 
2026        51102      14198