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         1678        613 
1994         2339        844 
1995         4439       1532 
1996         3605       1266 
1997         2337        797 
1998        23365       9848 
1999        14654       5623 
2000        40888      16982 
2001        41987      16387 
2002        33273      14848 
2003        62401      25862 
2004        49018      18813 
2005        87805      26948 
2006       113703      36261 
2007       208998      63929 
2008       130343      37018 
2009       105919      29728 
2010       122919      34077 
2011       185948      51389 
2012       171799      47515 
2013       268959      76241 
2014       668286     170426 
2015       781145     206994 
2016       573455     153686 
2017       539781     149627 
2018       411217     115401 
2019       925746     226194 
2020       722770     185594 
2021       931183     224128 
2022       696062     199113 
2023       647782     186377 
2024         1360        401