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          767        309 
1993         1356        504 
1994         1746        640 
1995         3288       1144 
1996         3203       1127 
1997         2288        782 
1998        23086       9740 
1999        14416       5526 
2000        39968      16571 
2001        40774      15882 
2002        34633      15183 
2003        59777      24829 
2004        47291      18145 
2005        83020      25544 
2006       107047      34305 
2007       196320      60502 
2008       117962      33667 
2009        97226      27371 
2010       111820      31164 
2011       165488      45851 
2012       156519      43342 
2013       231006      65751 
2014       574803     146598 
2015       749562     196194 
2016       669212     173290 
2017       570687     154160 
2018       367570     103149 
2019       889838     217376 
2020       642063     163659 
2021       862351     205437 
2022       639465     183036 
2023       578720     165694 
2024       510010     147433