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        60029      24534 
2004        46809      17864 
2005       311607     139989 
2006       337904     150547 
2007       197848      61151 
2008       115293      32955 
2009        96601      27086 
2010       147091      39185 
2011       155832      42560 
2012       183897      40682 
2013       241863      61386 
2014       541185     132865 
2015       771343     201230 
2016       623870     161051 
2017       539278     146544 
2018       328590      92432 
2019       838100     204797 
2020       569294     144195 
2021       778856     183485 
2022       589675     168891 
2023       536796     153627 
2024       586851     168657 
2025       603065     172382 
2026        52031      14505