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         3303       1149 
1996         3321       1168 
1997         2291        783 
1998        23113       9750 
1999        14432       5532 
2000        40015      16593 
2001        40861      15919 
2002        32078      14336 
2003        59937      24891 
2004        47353      18169 
2005        83231      25607 
2006       107399      34408 
2007       197251      60750 
2008       118791      33891 
2009        97720      27506 
2010       112531      31344 
2011       166706      46175 
2012       157337      43565 
2013       233238      66367 
2014       576827     147132 
2015       756370     197833 
2016       672081     174010 
2017       573286     154852 
2018       370287     103907 
2019       894473     218600 
2020       646064     164738 
2021       865620     206320 
2022       641506     183666 
2023       585108     167376 
2024       498899     144023