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          492        186 
1992          770        310 
1993         1356        504 
1994         1752        642 
1995         3315       1153 
1996         3370       1185 
1997         2291        783 
1998        23130       9757 
1999        14444       5537 
2000        40047      16606 
2001        40890      15931 
2002        32128      14357 
2003        60042      24932 
2004        47407      18189 
2005        83354      25644 
2006       107620      34472 
2007       197740      60884 
2008       119233      34013 
2009        97974      27575 
2010       112948      31456 
2011       167300      46332 
2012       157750      43677 
2013       234586      66734 
2014       577001     147224 
2015       699396     184547 
2016       673468     174360 
2017       574865     155251 
2018       371785     104318 
2019       896747     219214 
2020       648006     165272 
2021       867190     206731 
2022       642638     183990 
2023       586186     167814 
2024       470304     136727