Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
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          216         77 
1991          856        306 
1992          656        270 
1993         1176        442 
1994         1487        555 
1995         2362        834 
1996         2631        934 
1997         2509        857 
1998        23941       8554 
1999        12860       4904 
2000        36387      14945 
2001        41462      16284 
2002        35034      14992 
2003        57051      23369 
2004        44899      17104 
2005       303378     136698 
2006       330761     147690 
2007       191924      59455 
2008       108075      30830 
2009        88610      24788 
2010       136337      36314 
2011       143348      39007 
2012       170822      37070 
2013       225236      56699 
2014       472451     117244 
2015       711757     186158 
2016       600265     155120 
2017       505480     137442 
2018       301866      85366 
2019       804885     197195 
2020       528182     133866 
2021       711817     166618 
2022       552862     158566 
2023       510655     146301 
2024       550785     158315 
2025       524970     148942 
2026       362408      85458