Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          444        170 
1992          721        293 
1993         1283        478 
1994         1631        600 
1995         2897       1013 
1996         2895       1024 
1997         1787        619 
1998        21450       9127 
1999        12872       4961 
2000        37974      15682 
2001        39310      15236 
2002        33912      14786 
2003        56202      23427 
2004        45308      17408 
2005        79823      24597 
2006       102781      33057 
2007       187333      58090 
2008       106161      30512 
2009        89008      25144 
2010       141229      37986 
2011       150216      41722 
2012       141225      39184 
2013       214436      61150 
2014       545282     138795 
2015       794738     209145 
2016       644596     167360 
2017       543253     147037 
2018       337513      94896 
2019       848677     207202 
2020       590206     149693 
2021       801302     189522 
2022       607091     173788 
2023       546745     156461 
2024       605131     173853 
2025       506775     144491