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        12852       4901 
2000        36371      14937 
2001        41447      16277 
2002        35017      14985 
2003        57024      23357 
2004        44854      17085 
2005       303239     136641 
2006       330632     147638 
2007       191826      59429 
2008       107916      30787 
2009        88463      24750 
2010       136143      36263 
2011       143063      38929 
2012       170618      37015 
2013       224948      56619 
2014       472057     117144 
2015       711041     185972 
2016       599779     154989 
2017       504863     137264 
2018       301444      85252 
2019       804170     196991 
2020       527641     133715 
2021       710680     166365 
2022       552120     158360 
2023       510000     146114 
2024       550213     158154 
2025       524422     148788 
2026       364466      86121