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         2258        815 
1995         3362       1169 
1996         3570       1254 
1997         2326        793 
1998        23234       9797 
1999        14503       5561 
2000        40395      16760 
2001        42936      16648 
2002        32410      14487 
2003        60991      25294 
2004        47831      18347 
2005        84806      26078 
2006       110117      35198 
2007       202804      62243 
2008       124085      35331 
2009       100728      28319 
2010       117264      32589 
2011       175308      48489 
2012       163251      45145 
2013       251587      71191 
2014       597375     153091 
2015       723354     191894 
2016       707886     183163 
2017       598310     161477 
2018       393086     110163 
2019       926089     227338 
2020       678173     173655 
2021       890536     213073 
2022       661272     189115 
2023       614786     174084 
2024       269167      78043