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          532        200 
1992          936        367 
1993         1669        610 
1994         2329        840 
1995         4425       1527 
1996         3602       1265 
1997         2340        798 
1998        23328       9834 
1999        14615       5608 
2000        40717      16909 
2001        41773      16295 
2002        32925      14706 
2003        61931      25669 
2004        48633      18662 
2005        86941      26704 
2006       112609      35939 
2007       207572      63541 
2008       128459      36507 
2009       104470      29334 
2010       121393      33673 
2011       182949      50577 
2012       169664      46933 
2013       264539      75015 
2014       659685     168132 
2015       772135     204491 
2016       577998     154186 
2017       590399     157979 
2018       406585     114062 
2019       930236     227045 
2020       712112     182781 
2021       924347     222306 
2022       691370     197673 
2023       625341     179953 
2024       102541      29682