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         1749        641 
1995         3297       1147 
1996         3300       1161 
1997         2291        783 
1998        23100       9746 
1999        14426       5530 
2000        39997      16584 
2001        40843      15911 
2002        32069      14332 
2003        59906      24878 
2004        47327      18159 
2005        83135      25579 
2006       107227      34357 
2007       196858      60644 
2008       118423      33790 
2009        97526      27452 
2010       112227      31266 
2011       166155      46030 
2012       156900      43447 
2013       232173      66076 
2014       575972     146903 
2015       753005     197007 
2016       670843     173696 
2017       572197     154561 
2018       369019     103551 
2019       892193     217987 
2020       644483     164321 
2021       864258     205946 
2022       640614     183408 
2023       584742     167358 
2024       512202     148035