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         2834        992 
1996         2847       1008 
1997         2861        977 
1998        24573      10332 
1999        13406       5115 
2000        37671      15537 
2001        43216      17008 
2002        40387      16941 
2003        59718      24432 
2004        46728      17837 
2005       311522     139955 
2006       337838     150522 
2007       197690      61098 
2008       115290      32954 
2009        96596      27085 
2010       146799      39120 
2011       155624      42510 
2012       183881      40678 
2013       241839      61383 
2014       541182     132864 
2015       771417     201251 
2016       623829     161038 
2017       539163     146539 
2018       328419      92408 
2019       838170     204819 
2020       569268     144188 
2021       778611     183425 
2022       589575     168866 
2023       536764     153622 
2024       586007     168427 
2025       603028     172378 
2026        52329      14593