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         2628        933 
1997         2509        857 
1998        23939       8553 
1999        12860       4904 
2000        36377      14940 
2001        41460      16283 
2002        35029      14990 
2003        57041      23365 
2004        44878      17095 
2005       303320     136671 
2006       330711     147667 
2007       191881      59443 
2008       108021      30815 
2009        88553      24773 
2010       136250      36291 
2011       143222      38972 
2012       170722      37043 
2013       225133      56670 
2014       472290     117203 
2015       711486     186091 
2016       600084     155072 
2017       505266     137380 
2018       301685      85319 
2019       804593     197114 
2020       527924     133794 
2021       711320     166514 
2022       552582     158488 
2023       510482     146253 
2024       550516     158240 
2025       524792     148892 
2026       364225      86036