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          489        185 
1992          767        309 
1993         1356        504 
1994         1746        640 
1995         3285       1143 
1996         3084       1089 
1997         2288        782 
1998        23066       9732 
1999        14407       5523 
2000        39951      16563 
2001        40693      15852 
2002        31944      14284 
2003        59623      24772 
2004        47234      18123 
2005        82899      25504 
2006       106871      34255 
2007       195704      60338 
2008       117444      33525 
2009        96844      27264 
2010       111427      31063 
2011       164797      45664 
2012       155986      43198 
2013       229742      65395 
2014       554581     142141 
2015       715476     188631 
2016       661514     171621 
2017       568747     153680 
2018       365598     102618 
2019       887636     216779 
2020       639318     162928 
2021       859754     204750 
2022       638262     182694 
2023       577309     165277 
2024       583444     168237